It's also a little more energy efficient for you to use the hot water that their boiler has heated, rather than use their electricity to heat cold water when they already have a tank full of hot water in the house losing heat into the atmosphere
BUT
(sorry to get into the heat debate again :
)
My opinion on hot water rinsing - I often rinse with cold tap temperature water when using M-Power, but if I make a decision that the rinse needs temperature because of the soiling substance (greasy carpet for instance) then the water needs to be HOT HOT, not "hot tap" temperature. I think, for rinse performance purposes, you may as well be using cold tap temperature unless it's REALLY hot.
I've proved this recently on a restaurant carpet where their tap water is pretty hot, It was the first time I'd cleaned it with M-Power rather than detergent so I wondered whether the cold rinsing theory would hold up. I started rinsing with the hot tap water and it just didn't feel or look as if the rinse was shifting the crud very well. I stopped, whacked the temperature up to 90 degrees in-tank and noticed a significant difference.
Obviously apart from rinse performance, some state that there's a difference in drying between cold and hot - I'm not convinced. I've never had such an enlightening experience to form an opinion either way.
That 300cfm is tempting though, but the thought of having to purchase an inline heater and then all the hassle of using it, tripping over cables, extra set-up time etc... puts me off a bit. I suppose the only answer to having a machine that does all of that internally is 3 power cables. I run a ninja with 2 cables and sometimes it's a pain in the butt finding 2 sockets, let alone 3.