Thanks for the replies @ Dryce, Mr Perceptive, gad-westy, Cuchulainn. I think that's a really good point paying the extra £100 in order to get a valid UK warranty, so yes, I'll skip a grey import this time. I watched a youtube review the other day where the reviewer had bought the silver version and had to return it under warranty because the silver paint on the hotshoe was peeling off. So yeah, if I was unlucky enough for something like that to happen it'd be best to have a warranty.
I've just pre-ordered one in silver from
Park Cameras and they say they've got their next batch of X100vi being delivered first week of September. They'll call me when it's in and hopefully they'll have a silver one. Meanwhile, I'm told the London shop has one on demo so I'm going to try one out as I've heard the grip is a bit slippery. I can't use a grip though as I'd lose the hotshoe for my flash.
I had already watched a review of the 28mm lens converter but it ruins the aesthetic a bit for me as it's a bit on the bulky side. So I think I'll just stick with the fixed lens and if I need 28mm I'll use my Ricoh. Thanks for the help guys.