Clive - No!
The Jos/Doff/Thermatech whatever they are called this month are too slow.
I worked on a Tesco storefront last night, block paving to three sides, priced it for 2 nights, finished in one, with cold water alone. I would say the gum was medium density.
No matter how you clean the flooring you will still have to spot remove gum, i've got dry steam machines and if it was my job I would pressure wash the flooring, have two lads behind spot removing gum, with either the dry steam machines or hot pressure washers.
If you don't have the set up either hot pressure wash the lot, with spot gum removal or cold pressure wash the lot and then go back and hot water the gum and rinse.
Take my word for it that a hot pressure washer will be quicker than a 7 LPM Thermatech box. If you want to ring I will explain
Rob