HL to ii SIPP transfer

[Rollin]

I'm about to transfer my SIPP from HL to ii as I believe in my case the charges will be cheaper.
This has been complicated slightly as HL gives a discount on the OCF for some funds which assume won't continue under the ii platform.
All SIPP investments are funds, 50% of which are Vanguard. I'm wondering if it would be better to move these to a Vanguard SIPP as I believe the charges may be cheaper again.
Is it possible to move some to one SIPP and some to another?
Would these be in specie transfers as it looks like it takes weeks to complete a transfer and don't want to be out of the market (won't need to buy or sell).
I like to keep things simple and that would be to leave things as is, but I've now realised how high the fees are.
Thanks

[C69]

Do you regularly rebalance the funds held within your SIPP, or swap between funds?

The reason I ask is that ii charges £3.99 per fund trade, while the equivalent figure for HL is £0. This might be a factor if you do a lot of trades each year.

Personally, from an admin perspective, I wouldn't bother splitting my SIPP between different providers. Depends how much you're going to save in fees, I suppose.

[Rollin]

The SIPP gets a chunk paid in around March time and I drip feed about twice a month.
I suppose I'll need to check number of annual transactions to assess any savings better.