I use a stinking Helix for rehearsals, using the amp & cab sims through high dollar QSC mains and it absolutely blows... For live gigs, I use it for a handful of effects (delay, chorus, phaser) but more importantly, have a couple of the channels set up as an emergency "limp home" rig that I can go straight to the board with, in case my amp goes down.
I had a Friedman amp (Runt 50) go completely dead during a gig after 4 songs and at the time had a Tech21 SansAmp Fly-rig in my gearbag to limp home with and that REALLY sucked, lol...
But I can honestly say the digital thing doesn't come close to replicating the feel, depth and that intangible "aliveness" that exists between the amp & guitar/pickups as well as under the fingers. I have 6 different tube amps and every one of them will eclipse the Helix or Kemper.
I also have used a Kemper for rehearsals which also was... Meh. I'd rather use a Fender Tweed of some kind + some pedals.... Or ANY tube amp.
The other guitarist in my band exclusively uses the Helix and he FOREVER begs me to hear this channel or that channel/setting (which sound exactly like the last time) after days and hours of dicking around with knobs and menus, etc... It absolutely would bore me to tears or make me smash the f'n thing with a hammer and I OWN ONE.
Give me one of my tube amps behind me with one of my 2x12's, or give me death. To me, it's TOTALLY worth wheeling a road case containing my cab, from my truck to the stage... And the day it's not, I'll start shopping for dresses and/or quit gigging.
ANY newly-created channel that my band mate puts through the PA completely suck vs. A good amp when you really listen to it. There's no punch... No balls. He, just last week, picked up this Line6 "Power Cab" cabinet after I think, feeling buried with his **** tone by my Friedman Wildwood Smallbox 50 (Plexi)... I had to read 2 days worth of texts of "You cannot tell this isn't a real amp" "I guarantee you'll be buying one for your Helix".... YAWN....
Just buy a f'n amp & cab, already... Jeez