Tom, I had caravans for 20 odd years and now have a motor home. I have never experienced problems either way. I have observed friction sometimes between different factions e.g.
Those with badly behaved dogs and children and otherswith or without children.
Those with dogs and others with and without children.
Those who want to stay upall night having parties in their awnings and those who don't.
In general though I find things on site are harmonious with people getting on well or passing the time of day but no more and those who ignore all others.
Tom - in 25 years I've not noticed any friction or snobbery between motorhomers, caravanners or tenters.
Inconsiderate "campers" use all forms of living accomodation and bring all sorts of entorages with them - it's the inconsiderate that cause problems, not their classification.
As a caravanner I've always found motorhome campers to be very friendly. I've often been invited into motorhomes for a look round as well as for the occasional drink.
Many motorhomers have bikes, motorcycles or cars which they use for local travel when they're away but we've often given lifts into town to some who we've made friends with who don't have alternative transport. It helps to break the ice and we've stayed in touch with one or two who we've been out for meals or day trips with.
Like Parksy, we've also had positive experiences with motorhome owners, particularly in France, where we've had a drink or a look around a Dutch, a French, and a German motorhome (very nice, all of them, and the owners too).