I have had a speedpress for years and use it all the time, there are a couple of tricks to them I have discovered or they would be basically useless to me also, first,
#1, I buy the film from nglantz, I am not sure if they still sell it but I bought a medium tack and basically rarely change it, because I have discovered trick-2
#2-take a sponge with water and clean the film every so often before you use it, just use water although the last time I used a little windex and then water, and rinsed the sponge a bunch of times. Note, let it dry before you use it again.
#3 I don't fuss about the tightness of the film, I just slide a metal yardstick (sometimes I use 2 yardsticks) under the film near my work to keep the film and vinyl from "grabbing" and applying itself in the wrong place while I am positioning. Just position and go to step 3
#4 I don't use the rubber roller they give you, (this roller works great for tape hemming banners though) I use a felt squeegee, position your graphic, then start in the middle and work your way to the ends, I can knock out metal parking lot type signs really fast using a speedpress and I would not want to make even one of these type of signs without it any more.
Take away even 1 of these tricks and I would walk away from the speedpress also.
Although I print 99.9% of my banners nowadays a speedpress work great with cut vinyl on banners.
ps once you get the vinyl pressed onto your substrate, you have to shove your hand under to lift the speedpress away from your work, this takes a little practice until you get the feel for it.