I have SRAM x9 3x9 speed twist grip shifters, and a 3x9 cranks set. I need a new front derailleur, does anyone know if the sram x0 3x10 front derailleur work with my components? Or do I need to stick to a 9 speed FD?
Generally speaking a FD is a FD is a FD. It doesn’t matter what you use. If your x9 FD worked, a X0 will work just the same. Why not ditch it loose tow of your rings and the cable and shifter, simplify you ride and loose almost a pound off the bike?
I’ve toyed with the idea. I almost never use the little ring, even on steep climbs. I run a 53/39 with an 11x23, and I can climb all day in the 53-23 combination. The problem is that the times when I use the 39 I’d be totally effed if I didn’t. I also like the chainline of 39-17 better than 53-20 or whatever the equivalent combination is (you get my point about the cross-chaining).
If you ditched the inner ring, and accordingly the FD and shifter, what was it that pushed you to take the leap?
I think if I did this I would put one of those 3rd brake lever things on the aerobar I took the front shifter off of. In that case, I’d go with the Metron bar-end shifter for the RD to match the brake lever 
I installed a SRAM XO 2 x 10 fr. der. last week onto my 2 x 9 drive train, using 3 speed XO twist grips…it works just fine. Initially I was concerned that it may be slightly narrower for the 9 speed chain, but appears to not be an issue. You should be just fine