what speed you record at for reliablity really depends on the recorder.

there are a few recording modes: CAV, CLV, and PCAV.

CAV and PCAV are variable speed modes -- they write faster as they get to the outside of the CD.

CLV mode records at a set, constant speed.

basic rule: determine the highest CLV speed your writer will write at (which is almost always lower than its CAV/PCAV speed) and use that. that way the speed will never change and the write will be constant and consistent.

ive burned probobly 100+cds out of my laptop and played them in cdjs with 0 skips ever (cept one cd that took a spill down a flight of concrete stairs, and became scratched to hell)
Ive used all common forms of cdr media that can be found at best buy and always burn at 52x.
Speed has nothing to do with quality of the write.
So long as it isnt a $5 cd drive you have nothing to worry about, with burning your cdrs at speed.