Have had solar for about 18 months. Moved to Ecotricity when we set that up - were on Electric Kiwi and just went with the higher buyback. 

With line charge increases, any buyback "credit" mostly just offsets those at this point. 

Had a few delays in the first bill runs - but that was resolved pretty quickly via emails.

Don't recall having to need to speak to anyone.

Their customer portal is basic - but does the trick. I'm on direct debit, and that's all been fine.

Friends got solar at the same time and went with Meridian, as they had dual EVs and the plan worked out better for them. 

Powerswitch makes it all pretty easy to move IMO - so unless you're locked into a deal - it should be fine if you need to move.