I have my insurance with them (alexander swan), they are first class.
If my van gets stolen or is off the road because of an accident, they provide me with a courtesy van with a 600 litre ionic thermopure system installed for as long as i need it.
It was slightly more expensive than elsewhere (about £52 a year more if i remember rightly) but to me, having my van off the road for even one day is gonna cost me more than that.
Not sure about them only insuring if you have an ionic system, didnt know that.
Highly recommended IMO, speak to sarah she knows everything there is to know and is helpful.