John
I have 2 airflex minis
1 with the the in built heater and they are really hard to take upstairs .
And the one with the heater weighs loads .
Yes Neil , my alltec express started off with a built in inline , although i could drag it upstairs the heater was heavy and i since removed and i use an external inline . ( some express machines and sensei's have an emersion which weighs nothing and would def be a help if you get to an eot before the plumber arrives to fix the water heater ) My express now has one 6.6 and one HD electro , people have different strength and levels of fittness , i would be medium ,but i can either bump it up stairways on the back wheels or lift the whole thing in my arms for one flight anyway .
One 6.6 on its own is miserable performance though .
I know u are pointing the OP to something lightweight , but the cub is poor value omo ... its a £900 machine selling for near £1800
For that 1800+ vat you could have a new 250psi sensei with HD motor (1300) and add the airflex booster pod (400) for decent performance .
Or you could have the new miniflex with 400psi pump and a hd+sd electro (1799) ( same spec as a standard enforcer)
Both those options will blow the single vac cub away .