I agree with all the advice given here. I'll add my 2 cents and reiterate a bit:
Knowlege is power - I wouldnt say to just move on, X-Cals are very decent bikes, but definately go out with someone knowlegable. It does sound like your fit might be off - My gut says you're stretched out too far and almost certainly too high on the saddle.
High seat post - Wow, Im disappointed some Trek guy said that. I usually feel like a child when I ride my mnt bike because I keep the seat way low (when sitting my knees come up much higher than I'd ever want on a road bike.) On mountain bike, you spend way more time out of the saddle. You also dont want to come darn hard on it so you need some space for your knees to absorb some force before your butt meats your seat. The Trek guys know that, maybe you got a new employee that was a roadie - cuz that does sound like he was fitting you correctly: for a road bike, not mountian.
Bars- You probably do want to trim the bars if youre feeling they are wrong for you, but I would definately wait on that until youre sure youre keeping the bike - can't un-cut 'em! Its all personal preference, wide bars help stability, but youre riding the kettles - so you have to fit those bad boys between some trees too. Wide bars go better with short stems. you might do better with a shorter stem, but again, riding with someone who knows well might help out alot.
Tire pressure - Personally, Im a tube boy. But I ride solo alot and it sucks if you puncture your tubeless and youre 8 miles out. Even if you carry a spare tube for emergencies, its a sticky messy job once all the tubless goo is everywhere. However, if youre feeling like youre not gripping, lower your tire pressure. With tubes, you can easily get to the minimum rated on the tire. Even lower if tubeless. Lower pressure = more traction (and more resistance too though.)
End of the day - You have to love your bike. If Low or no cost tweaks are not doing it for you, I'd look elsewhere. If the bars aren't carbon, anyone wiht a hack saw can shorten them for you: $0. Same for the seat post. In both cases thoug - dont do it to agressivley. A little short won't effect resale. Alot probably will.
An Invitation - Every Tue and Thr this month (trails permitting*) we will have a group ride out to Pleasant View. We leave from Capital Brewery slightly before 5:30. Meet us there! Or at the Pleasant View trailhead - look for a bunch of guys probably with a higher than normal number of Cap Brewery jerseys (though most wont be wearig them.) No club membership needed. Come drink after too! Definately some knowlege to be had here.
*Check this very site for if the Pleasant View trails are open. It looks likely they will be closed tomorrow and possibly Thr, but if the trails open, we'll be hosting a ride. (I will also be riding there tonight around 5 - green to black fade Trek Stache Singlespeed, 3" front tire. Name's Dave)