Cyclocross - New rear derailleur needed...

I currently have my S-works CX set up with a single front 42 and a rear 12-27 cassette with an ultegra med cage (broken due to locked pulley). I would like to get some more range because I want to keep it single up front, so I want to switch to an XT 11-34 and a single 44 front. My question is should I go with a long cage XTR M952 ($95) or with a long cage XT M750 ($57) or a med cage XT M760 (newest xt model) ($70). These are the options I can currently find to purchase in terms of price/performance. I don't know if the shifting advantage of a med cage outweighs the range advantage of a long cage. Is long cage for cyclocross just a bad idea?

the problem with a long cage is the shifting is slower and the chain is longer. i'm not sure it's necessarily a bad idea, but i wonder if running that extra length of chain, as well as the looser spring in the rd might make for sloppy shifting in sloppy conditions. i do know that the rage among mountain bike racers in these parts is for a road rd on a road cassette for quicker shifting. my guess is that, with a single 44t chain ring up front, you probably won't need the extra chain length a long cage will give you, even with the wide-range cassette.

Ive got a similiar set up. a 12-30 and a single 42 chain ring. I run an xt long cage with a single ultegra bar con. In index mode it does not run to well but friction mode works great. I have not been able to figure that one out? But with a 34 on the cassette I think youl need a long cage, anyone else on that???

I run a 42 front with 11x34 with a xt mid length and a STI shifter...no problems

I run a 42 front with 11x34 with a xt mid length and a STI shifter...no problems

After all the input, I'm leaning heavy toward that setup. I'm still confused about why shimano would sacrifice strength with the xtr just to shave 50 grams. I can see using a lighter material/same strenght, but I'm a little in doubt that they would reduce durability for that small weight savings. Everyone is screaming XT at me tho, and I really appreciate the opinions.

Well, I found a real deal at supergo and bought an xt 11-34 for $40 and I couldn't resist the XTR M952 Long cage for $89... And if I want to go with a triple front, I've got that option...