HW Xerun V3.1, which one?
 

I'm thinking about getting a Hobby Wing Xerun 120a V3.1 esc for my 2wd buggy, however, there seems to be 2 versions of it:

http://www.hobbywing.com/product_show.asp?id=284

http://www.hobbywing.com/product_show.asp?id=289

Can anyone tell which version is best for offroad?

My next question is, I already have the LCD programme card for my HW Just Stock esc, do I need to get another LCD programme card to use with the V3.1? Or am I ok to use the one I already have on both escs?

They are stock or mod. Read the specs and make your choice after what you need. Do mod.
You'll need a new box as the v3 software won't work on a v2

Depends what turn motor you plan on using with it. I would personally go for the 120a one (first link) The second link is the stock spec and is 100a. If your running 6.5t motors or close to, you will need the 120a.

Have a look at the SkyRC Toro TS120. Its a great little speedo and think are selling for £80 at MB Models! Admittedly, the tuning software is a little rough around the edges and the included fan is noisy as hell, but for me, its perfectly functional and a small price to pay for what you actually get in the little blue package!

Can get them a fair bit cheaper on the bay from hk. Good speedos, don't know what you mean rough round the edges on programing? With additional program box it's a piece of cake. Waiting on the bluetooth module for mine for a bit of phone app tinkering :thumbsup:

Yeah, I'm going to get the bluetooth box as this saves lugging the laptop to the track as well. Without distracting too much from the OP, the "roughness" is when using the PC app with the Skylink cable. As well as having to "Run as Administrator" to get it to work (not a major problem when you know this), the software always defaults to what appears to be a Chinese char set! Clicking the button in the top right of the program switches to English but its not as polished as it could/should be (when compared to other manufacturers PC applications). Oh, and no Mac version either...

I would suggest the full mod spec 120A speedo, as you know it will work with what ever you throw at it.

The programming card isn't easy to answer, as it depends which card you have. If you have the older one, it can be used for both the V2 and V3 spec ESC's, but not at the same time - you have to change the firmware on the box. However, the later boxes will work with both ESC's with no changes etc.