I hear you on the Receptor.
I use a four-space rackmount computer (a PC) for live gigs. It fits in the deeper Anvil cases just fine, and allows me to use a high-quality hardware I/O that works great.
It's no big deal to take a computer out. Fear of that is unreasonable--if you do it right. People who are doing it successfully don't give it a second thought. You just have to be smart about it, and keep it dedicated as a gig box. The protocol is simple enough...everything backed up, OS backed up, installs backed up, everything double-redundant. Then you're good. The bonus is that you can use it in the studio as strictly an offline tone-generator...and when you want the best most fastest new gig box, you can use the old "guts" for building a good internet surfing box, and stuff the rack box with a set of the latest greatest.
I prefer that to a laptop, for the reasons mentioned...but even a laptop is OK, if you just play it smart. As long as your cabling is completely off the ground, and you use a racked firewire I/O of some kind for connecting up to the amps and house, then you're going to be fine. Again, you just have to design a mission critical rig, and work out the kinks. It's no different than keeping an Udu drum from getting shattered. You just have to have the right cases, the right stage setup, the right racks, and everything's good.