QuickLoad thinks your load should be a little faster than you're getting, 2,798 from a 26" barrel. It says the 22.375" barrel would be 2,712. Obviously not an exact match for your conditions but it gives you numbers to compare. It thinks a 20" barrel would be 2,645 and an 18" 2,579. So, you're probably looking at a difference of about 65fps.
Personally, I see no difference in maneuverability between barrel lengths. I honestly don't understand it. I've used barrels from a 15" handgun to 30" shotgun. Never a problem. Carrying around a heavy gun is one thing but sitting in a stand isn't an issue and the difference between 20 and 18 is irrelevant from a weight standpoint.
On the other hand, no animal would know the difference between 2,700, 2,600 and 2,500 either, so it's all a matter of what you like.