I doubt it.. Ballistix rated for 2-2-2-5 timings will be faster at THEIR stock speed/timings than "valueram" rated for 2.5-3-3, which, in turn, is faster than the 3-4-4 stuff.
However, I doubt that AT RATED SPEED there's a significant difference. As long as you're dealing with branded chips (Infineon, Kingston, Micron, Samsung) and/or a reputable manufacturer (Kingston, Samsung, Crucial, OCZ, Mushkin), you'll be fine. Now, the off-brand stuff (i.e. "Spectek" or "Elixir") is suspect, especially when it claims to be 400mhz or faster. I've yet to encounter an off-brand PC2100 module (Even Elixir) that can't pass Memtest86+ overnight at stock speed timings and voltage. I've seen some cheap DDR400, though, that won't do DDR400 unless you're standing on one foot, baying at the moon, and hitting the Enter key.
Saying that OC'ing memory is more reliable at stock speeds is, in my opinion, saying that a Ferrari going 65 MPH is more reliable than a Honda going 65 MPH. That's plainly not the case. However, I'd expect both to outlast, say, a Daewoo.