My vintage rollers do not have a wind unit so no variable resistance. Variable cadence though. I use my C'dale with the brifters and indexed shifting. I can shift up and down to match the cadence on whatever tunes are playing. I have a large sliding door in my shop so I lock that in position leaving just though room for the rollers in the opening. With that, I have a place to shoulder bump on each side when needed. I've only ridden off the drums a couple of times. I can focus on technique. Good cardio for me and smooth riding, higher cadence than my normal "in the wild".
As to new bands: I've not checked lately but a year or two ago QBP carried new bands. I expect to not have trouble when I need them.