You wouldn't have much trouble selling the Original Size Vaquero Sheriff's model 45 for a premium price. While it is larger in size, that also translates to a safety margin for higher performance ammunition. The 44 Special in most factory ammo is a lot lower performance. Handloading obviously changes the situation some...and lighter weight means more recoil.
I personally would keep the 45...and try to obtain a 45 ACP cylinder for it. The 357 caliber Sheriff's model has been drawing my attention of late. I'm seriously considering trimming a 44 Magnum Vaquero down, although I have not gotten much accuracy out of 4 5/8 and shorter barrels in the past.
Best answer is keep the 45 and buy the 44 Special. When you get old enough, you'll realize trading or selling any gun is regretted sometime down the road....with 40+ years of handguns, I can't begin to list my mistakes!