I'd go with the XL due to the upgrades it has for parts and in it's extra length. Stronger diffs, axles, axle cups, brakes, spur... lots of good stuff there even if you ditch the engine. If you upgrade the engine, you won't have to worry about drive train issues for quite some time.
As for the length, I know my 1" extended savage handles far better than my old school 21 savage ever did. The XL is even more extended I believe. Which should make it even more tame and better handling.