I would say it is too small, if you need a second tube you have to wait for it to warm one up. You really need to use a new tube with each client because you may run out half way through and then need to wait again.
The full size unit is actually quite good for mobile therapists, can hold your strips in the heater to keep the space tidy.
If you are looking at this kind of system, I'd also look at rollers - you have a much better selection of waxes to choose from then. The Hive Mini Multi-Pro is good, three tubes on the go, nice compact size and it fits both 80g and 100g cartridges.
Mat