I run 2 Kohler command twins and find them really reliable, cheap to service too if you buy the service kits from the states, just had a delivery yesterday and with postage it comes to twenty quid per kit which contains 2 litres of 10w-30 engine oil, 2 spark plugs,oil filter,fuel filter,air filter and air filter foam pre filter. one kohler engine has done nearly 3000 hours now and going as well as ever!
all the best
John