Sure there is. Most of them are more out east - Germany, Poland, Russia. Hardcore cavalry is mostly found in either France or Russia, for some reason.
More at home, I can only really think of the 7e BvL that fits the 'hardcore unit' description. It differs per event, of course. Events such as La Boissere are visited by people from all corners and groups, and it's pretty much as hardcore as you can imagine. Well, it was. This year it was a 'light version', due to shortage of participants. Do note it's not like all groups in the Netherlands are farbs - The great majority are people who spend lots of time and money into an accurate impression (uniform etc.). I know one guy, a engineer sergeant, who is probably the most typical beer-campfire guy you can imagine, and he has spend countless hours doing research to the uniform of the engineers and their role in the battlefield. They even made field fortification a couple of times. He is one of the many guys I know that, given the chance, they would love to participate in guard duties and patrols and such.
There's good news, though. Events and groups itself are more and more looking at historical accurate camplife etc. A new group doing light infantrymen is planning on having their cooks made in a historical organization (a group of men sharing one cooking pan, with a different guy responsible every day) and the general idea of more historical accurate behavior seems to rise. After Waterloo 2015, I'm convinced we will see a drop in numbers, but those will mostly be 'hobby'-re-enactors, while people who are more willing to become more realistic will stay. Plus, with less anniversary events, we will have more events of our own, where we can develop ourselves.
There's an event in november where they are already planning to have a march to the field and pre-battle skirmishes, and a 4-day event next year where the plans are...interesting.
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