Having learned the hard way, I thought it might be helpful to let other people know my experiences of these two companies over the last few months.
I bought some Mecatwin TT handlebars based on Mecatwin's website advice which states 'no need for new cables'. This is untrue and Mecatwin have since admitted that a longer brake hose needs to be fitted. They said that re-routing the throttle cables to the right side of the frame and unhooking the clutch from the frame is the solution to the short cable length. The throttle idea may work, but the clutch cable idea didn't on my Bonneville (2007). The bars also moved when fitted and Mecatwin sent an angry reply (with lots of exclamation marks !!!) to my request for a refund, saying that all I needed to do was rub down the flat surface of the upper clamp and it would work (quel idiot!). The theory being that this would create more of a gap between the clamp plates to allow more pressure on the bars. There was already a gap between the clamp plates. In any case, by this point the excitement of having Mecatwin TT bars had worn off completely and I wasn't in the mood for frantic rubbing.
I decided to write off the Mecatwin

experience, let my zen mind return and spoke with Norman of Norman Hyde, UK
http://www.normanhyde.co.uk/ . He said he'd been in business 30 years and evidently still retains the old time business ethos of 'if you please your customer he'll keep coming back'. He had the mellowness of someone who wasn't in a hurry to get off the phone and seemed genuinely interested in answering my somewhat naive questions (Tim of
www.Mototwin.co.uk is the same). The converse, 'if you sell your customer a pig in a poke then tell him to whistle when he realises then he definitely won't come back'.
The NH solution is the more expensive one, but I'm happy with the service I received and the assurance of a return policy that was customer friendly. They also said it is absolutely necessary to use longer cables and brake hose.
Issues that may have resulted in the Mecatwin bars not fitting properly:
1. Bad karma from the Mecatwin ethos.
2. Metric v Imperial: NH said that their bars are made to extremely high specs i.e. 25.4mm, and that they've rejected bars that they have received that were 25mm, for example. This makes me wonder whether the Mecatwins are a fraction smaller than 1".
3. Because some of the Bonneville parts are made outside the UK, it has been suggested that tolerances vary in the non-UK parts e.g. the handlebar clamps may vary. I don't have that much faith in UK production standards to suggest they're superior to anywhere else, but there may be some truth in the handlebar clamp issue because some Bonneville owners have fitted the Mecatwins and had no slippage in them.
4. No knurling on the Mecatwin bars. NH bars have no knurling either, but maybe they have the 0.4mm difference in diameter.
At the end of the day, I could probably have used shims, grip tape or other DIY solutions to fit the Mecatwin bars. They would have looked good but every time I looked at them I'd have experienced that inner slump you get when you've settled for something that was forced on you. My point though, is the importance of good customer relations to happy motorcycling. The last thing I'd want to be doing is negotiating a fast corner with handlebars that remind me of a sh**ty experience with an angry frenchman

.
I've also vowed never to eat another croissant
