I'm thinking of the XLR with the barrel cut back to 20". I'm not particularly interested in more velocity, I just think it will be a better overall package, velocity, noise, and pointing wise. I noticed a few of the customs seem to go for the extra barrel length also.
The guide gun seems like the best choice where the issue is compactness, But where that need is a little less, a slightly longer barrel seems acceptable. Anyway If I cut it back to 20" I can always go for shorter, it's harder to add back on.
I like both well executed pistol or straight grips. Really though, the mater was settled long ago and pistol grips are the standard so I don't see much practical advantage to the straight grip. I prefer the laminated stocks, depending on exactly what the wood composite is, it can perform better in wet weather, and it's also very strong.
I'll probably get the gun bead blasted and instal some of the reliability and performance parts like the sight upgrades, trigger, and ejector. After all of that it's probably worth looking at whether a custom job is just about the same cost! Maybe I should just stick with the guide gun.