I had handgrips installed on my 256s and thought I'd share some data points for those who are interested. IMO it is a lot more comfortable to carry the 256 with the handgrip.
The 256 doesn't come with a handgrip initially and I contacted Filson about putting one on mine. They asked me to ship it out to them in Seattle. The entire process took a little over 2 weeks and cost $20, not including the initial cost of shipping to Filson.