I think there is a 4th issue:
Selling it on; there is still the stigma of imported cars even if you can convince the buyer it s all the UK spec and more. You WILL be able to sell any car imported or not at the RIGHT price. But I suspect people are likely to buy UK supplied cars than imports generally.
This happened to me a couple of weeks ago, I was all set to buy a 4yr renault scenic at the right price (read: cheaper price) when I found out it was an import. Not having the time or knowledge to check it was UK spec etc. I declined.
The cars condition was excellent, low mileage, warranty was not applicable. But I didn't want it because I do not want any HASSLE whastoever selling on a car later or limit who may want to buy it.
When I told the seller my reasons; he was well annoyed, it sounded like the seller was let down again for due to his car being an import.
I also saved £7k (25%) on a perosnal imported car; making damm sure its was UK spec and more; but when I came to sell it; nobody wanted it at the time even though I offerd it a cheaper price. In the end I traded it in (& got the RS4

) and got less than what a UK supplied car would have got. I wasn't bothered as I still make a saving overall.
It was a hassle something I've learnt that I can do without in the future.