I come from a guitar background and still play more guitar than ukulele. I am fascinated by the thumb and thumb index technique and might try it some day. I think it is more natural for me to use thumb for bass and as many fingers that make sense for the trebles.
I currently have to deal with arthritis and of course this will continue and probably get worse. If I can keep moving every finger then that is best for me. Plus I get a real kick out of full on fingerpicking.