I liked the 105s better then the 99s, but I am leaning towards getting one of each right now. Most 105 frames are around even balance for possibly a little head heavy, but this one is more HL then the 99s by 2pts. The 99s is only a half an ounce heavier, so it is not a huge difference....for me the feel was no difference. My doubles partner and I hit singles for 15 minutes, and he is very heave and deep topspin, but I stayed in there and and was able to take cuts at his balls and hit winners with the 105. We were both new 4.0s this year but went 8-0 in league play, so we are likely moving up to 4.5 at the end of next season if we have another good year.
I did not even notice that the 105 was longer, and just read that it was 27.5", but it felt very very solid. It was more forgiving on off center hits then the old Steam and the Juice to me....and the new Pro Staff line. I would put it along the lines of the K-blade.
I am really really considering 2 of the 105s since I did like them so much and up next to each other the only difference with the 99s is that beam size just a little bit. The beam on the 100 Juice seemed enormous for me, and the power was way too high with that frame, this one was a little smaller and not a launcher. Hope this helps, sorry for repeating some stuff
Just get out there and try them both, it is the first wilson I have demo'd in a long time that I loved and have to have.