Hi all!
Just wanted to tell you of my experience in doing this voltmod.

I currently have 4 Gridseeds with the 5V fan mod running bfgminer on minepeon on a raspberry pi. From day 1 I did the original resistor mod and found 3 of them to run at 950mhz fine with no HW errors but one of them just didn't want to play nice. I ended up running that at 850mhz.

I then tried doing the 36k -> 38k resistor mod and pencil mod to the gridseed that wasn't playing nice. Found that this didn't really make a difference and I kept it at 850mhz as any higher would produce some HW errors.

Just last night I decided to do the new resistor mod. I resoldered the 36k resistor back, unsolderbridged the original resistor mod, rubbed out the pencil mod and followed the guide to solder at 39k 1/8 w resistor to r52.

This raised the voltage from 1.15v to 1.37v measured across r52 and the gridseed runs stable at 950mhz with no hw errors. I'll be replacing the resistor with smds when they arrive.

The original 3 gridseeds that ran fine at 950mhz consumed about 7w of power whereas the new gridseed with the new voltmod runs at about 10.5w. For reference, the fans used approx 1.5-2w of power.

Edit:
Forgot to include hashing rate stats!
about 12 hours up time:
the original 3 running at 950mhz hash at 404kh/s with an effective rate (calculation includes rejects and hw errors. Column 3 of bfgminer) of about 380kh/s on avg
the single newly voltmodded one running at 950mhz is hashing at 388kh/s (not sure why its reporting so low compared to others) and an effective rate of about 400kh/s

I want to thank everyone in this thread for all the information about the overclocking of these devices =D

If anyone have any questions feel free to pm me. I'm located in Australia so my timezone in out of sync with all you northerners =P (winter is coming.... )