Frank,
Personally, I am considering moving my SIPP away from HL and into a managed equities fund. The costs are similar, but I don't have a myriad fund managers all doing their own thing with variable results, and charging well whether they perform or not.
I have just moved into Drawdown, and am frustrated at not being able to take as much income as I would like due to the GAD constraints (nothing to do with HL). I wish I had far less invested in my SIPP, because it is likely I will end up with a sizeable pot remaining on my death, which will be taxed at 55% before going to my estate, far outweighing any tax relief benefit I received going in.
I'm not an adviser, but I wish I had put the maximum into PEPs and Stocks & Shares ISAs for the past 20 years, rather than a pension. It's what I will be doing going forward.
Good luck.