Cyclocross - New CX Build - Components?

I recently decided to build my first CX bike. I actually have a connection for frames so I was able to get a brand new carbon CX frame on the cheap. My problem comes in the components. Without thinking, I purchased an Ultegra 6700 group with a compact crank and 11-28. Then, my brother pointed out that a.) its going to get abused doing cx, b.) I should use some MTB components like RD and FD so they can be used for multiple seasons whereas Ultegra may be thrashed after just one.

Has anyone used MTB components for cx? Does this work? Is there an alternative? I noticed MTB FD's and RD's are 9 speed but any STI levers I can find are 10 speed. I looked for some 105 9-speed but everything is either in crap condition or obscenely expensive. Can I make this work somehow?

I was considering selling the entire groupset and purchasing a Rival groupset, but NO ONE around me is a fan of SRAM.

Its almost like I cant win...

Can someone please help me put together a component set that would be ideal for CX with comparable quality to, say, a Rival or Ultegra groupset? I dont care if it turns into Franken-bike

I've seen plenty of people use the Ultegra stuff for years of racing. If you already have the stuff, ride it, you should be fine. I used the Rival group last year, and beat the crap out of it and it's still ready for this season as well!

I am moving from 9 speed Ultegra to rival this year. My Ultegra stuff is still in good shape but I'm always worried that I'll dive one into the sand and it will be toast. Rival is rebuildable, that is a huge selling point for me in cross.

Send me all your 9 speed stuff!

I can't afford high dollar parts so used Ultegra adorns my ride and I'll just have to go to ebay to replace it if I spill hard.
I'm going to try and get in the habit of cleaning the bike meticulously after dirty rides. I went on a very sandy ride last weekend and need to get into some areas and clean residuals out after the bike wash.
Either way, I'd rather ride it than shine it and hang it ona hook as a museum piece.

What bigfo said. Ultegra is awesome, a lot of people use Ultegra with great success. I like Rival and will never leave SRAM as I believe it is close to the perfect cx group - light, cheap (relative), and reliable. I pounded my Rival group last year with no worries. I keep a tidy bike though.

A bird in the hand, yadda yadda. Use what you have.

Also, it is a myth that mtb componentry is sturdier than road componentry.

Agreed, actually a long RD can catch sticks and stuff. Use road gear, there is a reason that everyone else does.

Has anyone used MTB components for cx? Does this work? Is there an alternative? I noticed MTB FD's and RD's are 9 speed but any STI levers I can find are 10 speed.

This doesn't matter. Speeds on rear derailers are about marketing only.

That said, there's no particular reason to use MTB components.

My Ultegra stuff held up all of last season, I actually bent the rear hanger but the RD was fine! Beat the crap out of what you have, buy used versions off ebay for backup...