I thought you said the LDT voltage or the chipset voltage doesnt help in stabilizing an overclock?
If you have CPU with a lower multiplier and are aiming for high overclocks which involve setting your HTT to 280 and upwards it is from my experiencing that increasing LDT voltage helps sustain higher HTT speeds and in turn keeps you a bit more headroom and flexibility that vcore would otherwise not fix...LDT voltage is also a must if you plan on running a high 1:1 HTT/RAM ratio
Chipset voltage is a must if you are overclocking your memory, particularily BH-5 modules and getting higher frequencies with slightly tighter timings...although TCCD and other ICs will benefit from a bit more voltage running through your chipset
Suggested settings if you plan to get the most out of your overclock IMO:
LDT @ 1.4v
Chipset @ 1.7v
And this isn't just from my own experience, when I was consulting OCZ tech support about tweaking my Rev2s they were all in agreeance in regards to increasing the two in order to sustain high frequencies with better latency overall...I'll be demonstrating this myself shortly