Does anyone here have any experience with the Jandd large frame packs, this one here..
http://www.jandd.com/detail.asp?PRODUCT_ID=FFPL

It seems like a pretty good option to add an extra 4L of capacity into the frame space at a reasonable cost.

I was thinking of giving one a try but can not find reviews of this larger sized one, only a couple of very basic reviews on the standard size one that they do.

Any info would be very much appreciated and if you have one kicking around that you no longer use then I might be interested in it : )

I can't comment on that one but I give this 10/10
http://www.jandd.com/detail.asp?PRODUCT_ID=FFP

I've had it on my Fat bike for years, through the washing machine a dozen times and it's still as good as new.