Sounds like a good idea to me- if I had a cross bike that's exactly the gearing I'd want.

I currently have a compact on my tri-bike. It works really well. I proably can't comment on whether I have enough of the in between gears (I have a 10 spd on that bike and don't need the real easy gears so an 11-25 is great in the back for that type of riding). With only 2 rings in the front I've found I can get away with cross-chaining pretty far (the bike has bar end shifters though so I can fine tune really well).

Another thought- how you'll be riding the bike may have an affect on how well you want to fine-tune the middle gears. On my road bike I like to be able to be in exactly the right gear. On my ancient touring bike (the one I use for commuting and dirt roads- kind of like a cross bike to me) I'm not so picky- it has a triple with a really big middle ring- I spend almost all my time in that middle ring- the back has 7 speeds and quite a range. On that bike I don't mind at all that I don't have every possible gear available in the middle (I tend to meander more on that bike and my whole mindset is different).