Mountain Biking - Performance difference between front derailleurs?

I've only ever run Deore front derailleurs for singletrack/XC riding and I've never had a problem with them. Keep them clean and adjusted and they have always worked great. Now I have to use a Deore FD on the bike I am building (because of the chain ring sizes) and I was wondering if I should use the Deore FD I currently have on the Rockhopper and upgrade the Rockhopper. I can get another new Deore cheap but will I see any performance difference by going better? Any thoughts on the SRAM X Gen versus the Shimano stuff? If I did go up, I'd look at the XT or the SRAM.

So basically, the pros for the Deore are: cheap, as light as the XTR FD, and have worked great for me. I don't have any cons because like I said, I haven't used any others.

Any input?

I found the best performance running single ring.

im running deore lx for my specialized rockhopper. havent got any problem since the first day. keep in mind that i never ever tried to adjust it even once and that stuff sits on my bike for already 1 year plus. i think that fd derail doesnt need to be highend. as long as it shifts accurately, im happy. not sure what so good about xtr FD though.

I can't tell the difference between a Deore and XTR, they all work the same, and a front derailleur isn't exactly a precision device. It just mashes the chain in one direction or the other. The new SRAM is nice, but doesn't like double ring setups for whatever reason.