I have a .40 Hi-Power (and have previously had 2 others-all in .40). Yes, owning a Hi-Power is a type of a disease...
Whether or not the Hi-Power represents an actual improvement over the 1911 or is just a clever way for FN to avoid marketing/patent infringements with Colt depends upon who you read/talk to...
While I tremendously enjoy and appreciate my Hi-Power, there are some serious caveats to consider when comparing it to contemporary comparable pistols:
1. They're pricey. New Hi-Powers, even when significantly discounted, hover around (or above) the $900.00 point. And that's when they're available-importation numbers (presumably based on demand) seem to be fairly low (and the .40 varients reportedly has been axed from the 2011 production line-up).
2. Despite the svelte overall size of the Hi-Power, there are some questionable ergonomics-Despite improvement over the original design, the manual safety levers can be hard to engage/disengage, and tend to have a less discernable feel than the more positive engagement "click" inherent to the 1911 safety. The spur hammer is sharp, and somewhat long, which can "bite" some users. While usable, the slide release's shelf is less than ideally pronounnced, making the overhand or slingshot technique a more effective means of going from slidelock into battery.
3. The magazine well insertion point at the receiver butt is square, and relatively unbevelable, making for dicey speed reloads, even with practice.
4. While operationally I've literally never had even one, the smaller sized ejection port at least theoretically is more susceptible to stovepipe jams.
5. The finishes on Hi-Powers (both blued and the teflon epoxy) are at least a generation behind in protectiveness of the carbon steel of the slide and receiver-and the barrels are "in the white" (although I've never experienced any corrosion on any of mine), when compared to Tenifer, Melonite, Diamond Black/DLC, etc finishes used on competitors pistols,
6. Out-of-the-box triggerpulls are frequently, frankly, atrocious. Heavy, gritty triggerpulls seem to be the norm-inexcusable at the pistols' price point, and really inexcusable given the competition regardless of the pricepoint. To have to pay around $1000 and then to have to factor in an action job from the get-go by a qualified, competent gunsmith experienced in Hi-Powers (and they're a dwindling, and increasingly expensive fraternity) is an insult to a buyer's intelligence-especially given other more viable and less expensive alternatives these days.
7. Grips-while either style of OEM Hi-Power grips are certainly usable, there's a reason for the after-market cottage industry of alternative Hi-Power grips. In my case, when using either the OEM or (unfortunately) the beautifully crafted Craig Spegel grips, my triggerfinger actually protrudes too far in the triggerguard, past the first distal joint of my index finger. My solution has been to go with the Hogue rubber fingergroove grips, which acceptably bulk up the grip for my hand-and also provide a more viable grip on the frontstrap.
8. Magazine floorplates have sharp edges at their rear, which can cause discomfort in concealed carry (particularly regarding carrying a spare magazine)-juducious choice of a magazine pouches is highly suggested to deal with these sharp protruberences.
9. Trigger reset consists of...letting the trigger go all the way foward (as opposed to "catching the link"/reset point earlier in the trigger's return travel). Yes, there are gunsmiths that can reduce the reset distance. Yes, they're expensive...Again, with a Hi-Power, the more usual technique is for the user to adapt to the characteristics of the tool; but comparatively, there are other contemporary alternatives that have a shorter, more discernable trigger reset point, reducing shot-to-shot times.
10. The magazine safety (present on all Hi-Powers except for 1942-1944 Hi-Powers produced under Nazi occupation, and immediate post-WWII production guns) is of questionable real-world utility, and provides yet another "glitch point" in the Hi-Power's triggerpull. While the magazine safety is removable, to do so also precludes one from using the Hi-Power in some competition venues, such as IDPA...
11. And, on the .40 Hi-Powers, the recoil spring is quite heavy, making for more effort required in manual slide reciprocation (cocking the hammer first is a recommendation here) and reassembly after field-stripping.
If it sounds like I'm against acquisition of a Hi-Power, I'm not-they're superb guns, naturally pointable and usually quite accurate, with excellent sights out-of-the-box. I've found them to be quite reliable, within their forecast life expectancy (likely around 12,000-15,000 rounds for barrels, 30,000-35,000 rounds for the guns themselves). The durability issue may be a significant show-stopper, especially for heavy users-and the 9mm varients are NOT suggested being fed a diet of +P ammunition (the .40s, with their beefed-up slides and components seem to be doing fine, and Cylinder & Slide apparently has had a viable conversion business in offering a conversion of .40 Hi-Powers to 9mm, using the strengthened .40 components and a Bar-Sto 9mm barrel, offering in a sense the best of both worlds).
In short, for a "one gun" person desiring a viable combat/defensive handgun, I would tend to suggest going with Glock G17 or G19 in 9mm (far less expensive, more durable-and the Gen4 Glocks with their alternative size frame backstraps, larger magazine release button, and revised grip area surface treatment might successfully address your comfort issues with previous Glocks) or an HK P30 in 9mm or .40 (superb engineering, significantly pricey, variable aftermarket support/parts availability-although contemporary reports have been very complimentary), to name two alternatives-and there are certainly others (frankly, I'm quite pleased with my very late production P89 for a DA/SA pistol-but they've been discontinued since late 2007).
While viable, given the state of available contemporary handguns, I find the Hi-Power to be be enjoyable, but somewhat obscelescent-not necessarily obselete per se, but the competition has moved far beyond it, especially for heavy-duty use in challenging environments. There are quite simply better choices available, in my opinion, given the original poster's criteria.
Best, Jon