it's called "live performance" notice that it's 2 simple words, and it doesn't include any specific information on what you're using or how you're doing it.... it's possible to do a good live performance including a laptop on stage. you just have to be able to perform with it and whatever else you have up there. (and it does really help if you have other things to play!!)
Just because something makes it easy to be lazy doesn't mean you have to be lazy.
We went from years of playing all hardware to taking a laptop, about 4 years ago, and never looked back.
Its funny that people always like to go on in these threads about hardware being more reliable than a computer -
I've had an Mpc fail live (was the 2nd one, doing percussion parts so no biggie.. but required taking home and faffing about with inside to fix. if it was the only MPC we had, or was running the main sequences, would have got really messy)
I've had a waldorf XTk fail live (that was a disaster, as it was meant to be running all the main synth parts, sequenced from an MPC, and a power spike took out the internal PSU, killing it completely till I went and replaced the PSU) Lucky we had a minidisk backup plan, or there would have been no show!
Yeah, we've had the odd bit of PC weirdness, but no show stoppers - and if you keep your system light (read - dedicated to performing live! and reinstall at least every year) stability shouldn't be an issue.
benefits of using a PC over sequencer and samper -
1) no need to faff about with trimming samples to make them fit in limited sampler RAM - if it's a part of one of your tracks, you can render it out, chuck it into live, and use it.
2) no real limit to layers - when using samplers live, small space meant we had to mix down more layers into one sample. using the laptop gives more flexability.
3) faster to take elements out of your DAW and put them into live.
4) no need to try and recreate all your basic synth sounds on one main synth.
5) no need to try and recreate all your synth lines and drum patterns in one sequencer.
all these things mean less time spent housekeeping liveset data, and massaging your music into a format that you can even begin to play live with, and more time spent practicing performing.
6) real time timestretch - ability to tempo change things on the night to pull things down or push them up again. can't do that with loops in a sampler.
7) And unfortunately - the most important thing for some - if you get bored during your own generic crappy mnml laptop set, you can always play minesweeper or check your email....