Having ridden both a fair bit (in fact, there's a Chameleon sitting a few metres from me right now, though it's my wife's not mine!), I'd far rather do a daily 11-mile ride on a Chameleon than a Brompton. But the mudguards issue is a good point.
There are plenty of other folding bikes designed for longer rides. I ride a Bike Friday New World Tourist, which I love, but there's also Airnimal's Joey (which can take mudguards) and a bewildering host of Terns and Dahons.
Ultimately it comes down to space on the train, I think. If you're loading it onto a packed commuter train then really only a Brompton will do - they fold smaller, faster, and cleaner than anything else. If there's more space on the train, and you can stash it in the vestibules or a large luggage space, then you can get away with something less compact. I take my Bike Friday on the train reasonably often, but it's nowhere near as compact as a Brompton, and I wouldn't choose it for a daily commute on a busy train.
(Oh, and Chameleons have weird size rims. There's only about three different makes of tyre available for them.)