if its the only machine you'l have i would propably choose the tempest ... as you can bring it upstairs or handle any awkward situation .
And you wont absolutely need a seperate heater .
I see thay are fitting locking castors now , and they have a second heat system to complement the immersion ( probably something like powerflite perfect heat , or exhaust exchanger )
Another alternative might be twin 6.6 miniflex , but smaller capacity , no heat , bigger price .