All I'm gonna say is that I just recently started tying with real seal, both mature and baby. Baby is good for small flies, like small wet flies and nymphs for trout, mature is much spikier and buggier, and great on big nymphs and (especially) streamers. I've tried a few different subs and some come close, but none are 'practically the same'.

Mature seal is not hard to use at all. If the normal 'dubbing noodle' wont work, a dubbing loop makes it just as easy as can be. Dubbing loops are also, in my experience, more durable, so that's what I use all the time.