Every use case is different. I only mentioned it as it's something most people don't think about!
Mrs S even managed to continue a video call seamlessly walking from the house to the van and carried on while we drove off.
Well, I was driving, obviously, but you get my point!
Virtual SIM. Ah. Yes. Teltonika don't supply an adapter for those

(actually one of my only gripes with them is that they provide a set of SIM adapters, which is great, but it's a dual SIM unit so... They could have spent the exta 5p and supplied two sets of adapters)
Adapters - looks like they're TS-9 then (threaded 'nut' on one end going to a smooth cylinder with a hole in the centre on the other?) i.e. anyone looking at the Puck to go with an M1 wouldn't need to buy adapters as they're included now. Pretty cool!
iDmobile are very competitive.
£15/month for their unlimited everything plan - however they have a 'fair use' 30GB limit abroad.
That's pretty good as they use the Three network who have a 12GB limit included when roaming.
What I couldn't see with iDmobile was the option to 'top it up'. With Three I can buy a 'Data Passport' for £5/day which gives me unlimited and unthrottled data abroad.
They might have a similar option, but even Three bury it deep in their description and don't advertise it so it might be worth just getting in touch with them and asking.