After much searching and trying out different models and types, I believe that I have finally found the best set of mirrors for a 2009/10 Bonneville.
The stock chrome "rabbit ear" mirrors are very good cop-spotters, but spoil the outline of the Bonny somewhat, being so high.
The various bar-end mirrors I tried all had faults, some being too small, and all of them being too wide for trickling up between lines of traffic to the front at the lights.
The best made bar end mirrors I tried were the Halcyon's from the UK, but these had the 'too wide' problem in lane splitting, just like the bar end Napoleons did.
The very small CRG's and their various eBay copies had me peering at them trying to see further back than the back end of my bike, and spotting a fast-moving Patrol car sneaking up behind you at any distance was well nigh impossible.
The Triumph aftermarket mirrors were ok, but you had to fiddle around with the grips to get them to fit on the ends of the handle bar properly.
I tried all sorts of mirrors from eBay, looking for the "perfect" mirror for my black 2009 Bonneville.
Finally! I found them.
A set of black bolt-on Napoleons
These bolt straight into the standard 2009/10 mirror threads on the Bonny. Napoleon supply the bolts with the mirrors, you simply screw them on.
They look great, they work really well, you don't have to fold them in to lane-split, you can spot a cop a long way back, and the mirror adjustments all work excellently. They have a lovely low profile, and fit the look of the Bonneville beautifully.
Not only that, but with 28" wide bars you can fit the Bonny through some fairly tight spaces in traffic jams without having to worry about banging your bar-end mirrors against cage driver rear vision side mirrors...