To break it down to the three specific models...
Xenon, i've had two with this groupset, transmission wise, they've been flawless. Wheels (WS32 rims) have been bomb proof, no problems. I see they've changed to crankset to a slightly different FSA model. The Mega Exo BB isn't the longest lasting and is probably the only bit i've had to replace on mine, how the Vero performs, i don't know.
105, i see they have fitted the Mega Exo triple on this one, as above, the BB isn't the strongest, but i wouldnt not buy one just on that fact. Wheelset is the Tiagra (WH-R500). I have these on another bike, again, bombproof, but they're not light or high quality wheels. They do flex a little if you get out of the seat and push along, but again, i wouldnt not buy the bike just for that fact. Obviously you get the 105 groupset which is better then Xenon.
2300. Only 8 speed, lesser quality wheels than the Xenon and 105.
In essence, the Xenon and 105 are fairly bombproof bikes. FSA BB's i'm not keen on, but they may not be any worse than any of the competition.
With the 2300, you're buying a good frame with, dare i say, lesser quality components. You could upgrade later but i'm not sure thats an economical way of doing it. I'm sure its an ok bike, but you sacrifice components for the price.