So having spent the last 5 years attending milsim events all over the US and multiple different event companies, it all depends on the 'level' of milsim as to the level of cheating I've found.
Operation Lion Claws or OLCMSS was pretty much an 'entry level' milsim weekend. It is more like 2 days of skirmishing with no high caps. I found 'no hits calling' to be rife at the couple of OLCMSS events I attended.
American Milsim or AMS is definitely what I would call an 'intermediate level' milsim event. The medic rules are adhered to a bit more by players and in turn the players all seemed to buy in to the event a little more. Quite a bit of God mode but not so much that it ruins the event unlike above.
Milsim West or MSW is a full on LARP milsim that requires the player to fully immerse into any role taken on. The whole event is geared towards 40 hours non-stop and no returning to a car or hotel. Bashas are dug and sentries are posted all night. The use of NVDs is widespread so the event is for the full 40 hours, friday evening to sunday afternoon. BBs are limited initially to 300 per person (2000 to support wpns) which encourages them to be used in a more support role. The Insurgency format takes this a step further and airsoft almost takes a back seat. strong medic rules, the use of a sim tourniquet and no dead rags but acting injured (screaming "i'm hit!!, man down!" etc") makes casualties (and the medic role) more fun.
Personally, I enjoyed some of the locations for OLCMSS events I attended (old paper mill complex for one) and loved the AMS events for the scale and size of event. but I attended far more MSW events (11 in 4 years) and certainly preferred the small details that sets MSW out from other promoters like the use of blank fire, the tourniquet, the expansive locations, the use of the cadre and the role players.
If anyone flies over to the US for an event, I can recommend AMS and MSW events for very different reasons.
Now to sample a ton of UK milsim events and see how they compare!