I'm afraid this is not going to be a complete answer, but it is a sort of answer, so I won't put it as just a comment (and after all, you asked for experiences).
I have never used the Turbo type, but have built myself a roller, actually a very questionable one, but it worked fine the winter I actually used it.
Regarding falling off, it never, NEVER was a real problem after the first ten minutes of getting used to it. I could spin as fast as 180 RPM (peak), and accelerate quite hard, without an issue. The "secret" is to have a proper distance between the rear rollers, so the rear wheel can "sink" a bit between them and stabilize the bike, and also to have the front roller in a neutral position so that it doesn't push the bike forewards/rearwards. This also makes it harder to roll, so if one wants to train "round stroke" the distance can be reduced, making the roller faster and more unforgiving. It's nice, and if you fall off, it's not at ACTUAL 30 mph...
Regarding adjustment of "hardness", for all my practical, self-determined purposes, the very own gear-shifting of the bike did it all. At the time, I rode mountainbike, and even knobby tires can work depending on specific tire thread and roller diameter.
I always trained regular riding style, playing with cadence/gear combinations. Half an hour was enough to wash the floor in sweat, but I suspect a better quality (not home made) roller would be more comfortable to ride longer. The effect upon my riding was very noticeable, specially the increased ability to spin fast at relatively high speeds ("Armstrong-style") for longer times, which can be an advantage over other riders.
I don't like, also, the idea of having the bike fixed, this seems like taking away what makes riding fun (balancing), and for orthodox training purposes, I believe it fulfills the needs of most riders.
Hope this helps!