I don't see MT making them illegal any time soon tbh. Secondly people need to realize that cleaning your gear is more important than not using felt. I find that any wadding boot you buy felt or not will still transport invasive species in the laces, mesh, and in side sole of your boots. This is why you clean your boats, same reason should apply to your wadding gear.
If you fish waters that are known to carry, clean with bleach please. Always wash your gear when traveling between watersheds simple as that.
With that said, I would recommend felt in many of our rivers if your mainly wade fishing. Or at the very least like Chris said studs help but nothing like felt. I have tried my rubber soles for my korkers in the rivers around me and fell all over, made fishing from hole to hole a real pain in the ass.
Plus 1 to the above and the way I've 'solved the problem' is with the new Korker Chorme with the interchangeable bottoms. Pick a bottom that meets the need. The 'felts' actually appear to be a woven pollie plastic of some sort. Will dry in under 30 minutes in a hot car (ditto the boot). Want studs in those?
Hit a 'Big Box' hardware store and get a box of #8 x 1/2'' "hex Wsher Head" sheet metal screws (best if you can find aluminum ones!) Fastest way to install is with a
TINY pre-drilled hole then insert the Hex Washer heads with a 1/4 ratchet. One in each corner of the heel and then every 2'''s around the out side of the boot bottom (I don't put any in the middle).
If you want to make the application even more secure a dab of Gorilla glue before screwing in the 'stud.' Once that glue sets up, the things aren't going anywhere.
One type of 'stud' that's even more '
aggressive' is the "Kold Kutter Racing" studs. This are the things are used on the bottoms of motor cycle tyres for racing on (of all things!) ice. Same dimensions as the stuff above. Any motor cycle shop (or on line) should be able to get these things for you.
But why the 'Chromes?' Top opens up to the size of a two gallon bucket (very easy on/off) and the Boa lacing takes seconds to adjust to any 'comfort level.'