I've tried both cross bikes and hybrids(mountain bikes and road bikes too) on my commute and I stuck with my cross bike. The main reason was the different hand positions. I have no desire to try anything else as I'm very happy on my cross bike. The inline brake levers are really nice to have for commuting. Drops are great for those windy days. Plenty of braze ons for racks and fenders. The bike is reasonably light unloaded and reasonably compliant with 28c tires and a brooks saddle.

About components, you can mix and match road and mountain bike shimano groups as long as they are 9 speed. I believe 7700 level dura ace(1 full generation old), 6700 ultegra (1 full generation old), current 105, tiagra and sora are all 9-speed. All levels of shimano mountian bike parts are 9-speed now. I hope that doesn't confuse you more.

I use tiagra/105/XT on my cross bike and everything works out great.