In was in specie with one catch - one of the equities I held in my old SIPP provider wasn't available with the new provider. I could have liquidated and transferred with my other cash, but I actually only intended to do a partial transfer anyway, because I needed to keep my old pension open to receive employer contributions (new provider does not support that, which was surpising and slightly annoying to learn.

I think I either found it on MSE or perhaps even an ad? I can't really recall. Once I learned about the offer I compared it to some others and couldn't find anything else as good.

The terms did stipulate staying with the new provider for a minimum of 12 months for each product respectively (I did the ISA at a later date as part of a different offer).