I tried cleaning my M in a cup of hot coffee and creamer..
Don't be blaming George lol, that wasn't his suggestion! You need high fat content, that's why he suggests cream, normal coffee is mostly hot water with a little drop of cream or milk, very low amount of fat there to dissolve the resins. More fat the better for that, cream or at least whole milk (without coffee or anything else in it).
I'd just use ISO too, but make sure you're in a well-ventilated area without any open flames - pretty sure they just don't want to be sued when some idiot takes his vapcap out of an open bowl of iso, slaps some weed in there and sets it, his hand, the bowl, his home, his dog or whatever else is nearby on fire.
My XL feels a lot better in my hand and I like that I have more space between my fingers and hot flame, because I'm doing this stuff stoned. Really I want a little longer than an xl and wider to feel comfortable, Lithe looks perfectly sized and shaped but...inhaling butane is a step back.
In case anyone's interested, lacentralevapour, I think I got that right, has an M, Vaponic and Lithe for sale as the 'Adventurer Pack', more or less buy 2 get 1 free.