I've just got a Tailfin to try it out. Normally I don't like roll tops as I think they are a pain to access and not necessary, but I thought I'd try it as lots of people rave about them. Not used it yet.
I'll be interested to hear how you get on Frank.
The issue with the rack-pack for me isn't, necessarily, the roll top it's more the 3 straps that you have to undo to get anything out of the bag. Then you have to connect them all again. With luck, they haven't dropped onto your oily chain.....I know there's a side pocket but that's too small to be any use at all.
OTOH, I love how stable the rack is and the mini-panniers are excellent and they don't wobble around at all.
Back on topic: I don't camp so I don't need a tent and all the other paraphernalia but I've found that even "rigidly" mounted seat-packs cause too much sway when I'm out of the saddle, hence my preference for the Tailfin rack.
I've also got a Tailfin top-tube bag and, on longer tours, I use a small frame-bag and a "quick on-off" Ortlieb handle-bar bag. The Ortlieb is useful for keeping valuables in and it also helps to even up the weight across the bike.
You can get a matching set of Tailfin kit Rabbit but it'll cost you. Rack-pack aside, it works really well.