[EricH]

No experience, except that I spend a lot of time on man-rated industrial scissor lifts.

If stability is important, scissor lifts of more than one stage should be rated as do not use. I walk from one end of a lift to the other, it sways a bit.

If simplicity is important, scissor lifts in general should be rated as do not use. (See: elevator system, pneumatic lift)

If you can't do much precision work... See the bold text above.

If you are seriously considering doing a scissor lift system, you should do the math. I've heard of engineers getting scared of that math. You need to account for all the stages, the stability, and the precision needed. It's not easy.