They're a totally different animal to bog standard investment funds so making an apples to apples comparison isn't really possible. They really are suitable only for a limited number of investors where the higher fees can be justified by significant tax savings that are required in a shorter timeframe than would otherwise be possible.
Here's some info: https://blackfinch.investments/iht
Ah so they take 2% up front (plus a possible intermediary fee for the advisor) then charge a 0.5% annual fee and a 1% dealing fee... I mean I guess if you're suddenly told you have only a couple of years left to live or so.... even then could just as well invest directly in a portfolio of AIM shares yourself I guess.