The front would have been a 24mm; BNF24Z
The 27mm BNF27Z is recommended for motorsport only by Whiteline; it's a very big increase. I think on the street you'd probably end up with too much understeer; especially in the wet.
The feedback I have had from the 24mm bar is excellent
The adjustment is very nice to have, you'll likely set and forget, but for no extra spend; it's certainly nice to be able to finetune to your own taste and to the behaviour of your coilovers.
I've delivered well over 60 sets of Whiteline bars to people on this forum, and I've never had a complaint about the quality. I've fitted several sets, and the fit has been excellent. I personally inspect everything prior to shipping, and I've never found a fault yet.
They are powdercoated in a Silver/ Blue metallic, and as long as you are careful when fitting, the powdercoat will provide excellent protection against corrosion. It is flexible, but will take a knock without chipping; like a painted bar will.
I notice you're UK based, so I can't help you with a Group Buy; but if you have any questions, feel free to shoot me a PM
Cheers, Dale.