Originally Posted by a2psyklnut
The debate between alum. or brass nipps is that brass is stronger and is easier to true. Alum is the weak link and will break vs. pulling a spoke out. However, alum tends to corrode and makes subsequent truing difficult.
I prefer brass.
If you're worried about it, then I use the Competitions and brass nipples. The piece of mind way be worth any weight difference (which would be pretty small anyway).
I have a pair of wheels that are 14 years old (rims and hubs) and the current spokes/nipples are probably 5 years old for the front wheel and 8 years old for the rear (long story for the front wheel...). Both are built with DT Revolution spokes and aluminum nipples. I would personally rather the nipple break than the spoke pull out and ruining the rim. I've never had a problem with the Al nipples corroding and making truing difficult. $0.02
Oh, and 3X is definitely a good choice!