Sorry Terry, totally missed this or I'd have been all over it! I'm a bit of a Frost River fan...
Think there is even one missing from this... Anyways, I'll be the first to admit they are not the comfiest of packs for long distance walks although I have managed about 6 miles or so with no trouble at all, I wouldn't want to do a multiday long distance hike with one but I don't do those so....
The main issue for me is the hang height of the bags and also having things jab into your back if badly packed. I get round this by inserting some floor mat like you get from B&Q, screwfix etc cut to size which doubles as a sit mat. You can just see the grey bit sticking up in this pic. The mats are like
these from B&Q I think I got mine from Aldis or something. I use the FR packs all the time when canoeing and they are great for that but they also work really well for short to medium day walks too.
Hope this helps,
Cheers,
Alan