In reply to Doug:
I have quite a few duffels of differing sizes and brands. I've got TNFand Patagonia - very little in it between the two quality wise. both have straps that become rucsac straps. Both have compression straps, Patagonia's are internal so possibly less to snag whilst getting manhandled. I have used a Gelert copy of TNF bag, okay for light occasional use, but if you know it is going to have a hard life then go for the more expensive brands as they are much more rugged.
I have a wheeled Patagonia bag. I use it when I take my tribe on holiday. I can fit a week's worth of clothes for myself and my 4 boys in (there's just the 5 of us, and most of the heavy carrying is left to me) in a 90litre wheeled back and a 40litre duffel(which sits on top of the wheeled duffel).
It's been thrown around quite a few baggage trolleys, trains, been on about 8 flights, and still looks like new after 4 years of service.
Yes, I used to be in the mtfu club, but a spinal injury (which is now much more stable) led me down the wheeled path. Now I am converted. (But not wheeled cabin baggage!)
Can heartily recommend.
If you want a Patagonia one look for the end of season sales on their website, as long as you aren't too fussy about colour you can sometimes get 50% discount direct from Patagonia.
If you are looking at one of the more expensive duffels, some have replaceable wheels ( taking standard skate wheels). Pretty sure mine does, but no worries, as with all Patagonia kit it has a lifetime guarantee (which I've used on an old jacket and is exemplary).
Post edited at 15:28