I can only speak for my experience with Campy. I have had both a standard double and a triple on my bike. I called Campy twice and spoke to two different people and they both told me that all Campy cranks have the same Q-factor. I guess they angle the cranks inward on triples.

I do not have problems with my triple but am planning on replacing it in the next year with a compact. Weight reduction is great but it isn't the reason that I will be going to a compact. I can put a 12-29 Campy compact on my bike and get the same range that I am getting with a triple. The jumps might be more on the compact from the 29 to the 26 but you don't notice the jumps as much on gears of that size. Where you notice the jumps is at the other end of the cassette and they are one tooth jumps on both the triple and the compact. So, I don't really see a down side to a compact.

The reason that I want a compact is that the gearing works better for me. A 50X29 is the same as a 42X26 and a 50X12 is almost the same as a 53X13 so I have eliminated one chain ring. Then, a 34X29 is the same as a 30X26. So, I haven't lost anything. I will probably go with a 12X27 instead of a 12X29 because I don't need the extra climbing gears.