An improperly designed isolation mount will have adverse effects on a gas, or any other engine for that matter.
All other engines in "planes, trains and automobiles" are isolation mounted whether they are piston pounder, turbine or jet.
I use isolation mounts wherever practical and possible and I don't use ones that let the engine "jump around" nor do I mount them that firm that the isolation mount might as well not be there.
Good Luck

Merry Christmas
John