Derek
the Flexi5 and the similar one that was on sale from Solutions UK are no difference in principle to the more expensive Host.
You vacuum with the brushes working only in the dry situation.
You wouldnt want to vac the prespray would you. (think about it).
So, with the Envirodri, and small Sebo, you would need to agitate to loosen dry dirt, then get the vac onto it.
With the combined units you do this in one action, thus saving time, then you prespray and then agitate only (vac off)..
So, Once you prespray, you use the agitation only, to help the fluid do its job.
They were good value for money, but as Mike has reported, their seems to be a problem.
Spencer Davies took one of the new Prochem, but I think that went back with a problem. Whether he got a replacement - dont know and he doesnt seem to frequent here much now to answer..