ORIGINAL: Austin/WI
I got to shoot the Katera and the Katera XL during spring break, along with a bunch of other bows, and I prefered the XL over the regular Katera. You're guess is right on, I thought the XL was much more stable post shot and while holding steady at full draw as well, just more balanced overall to me.
Exactly why I liked the Trykon XL much better than the Trykon, and why I keep looking in the classified here there and the other place for a Vectrix XL used. I also like the Seven37 I shot as well, but I've not expected to see a used one of those show up anytime soon at a bargain price.