I have to say a big thanks for all the comments/advice etc, as usual, good stuff. We are still chewing on the deal, must decide soon!!
Let me throw a spanner in the works and suggest that you do not exclude a nice, used, 2013 or 2014 Plus 8 from your review process. All the joy of a modern V8, plus if you want it, an auto box option and a chassis that is more than capable of taking the 367bhp power.
I felt that our 2009 Roadster showed that the trad chassis was at its limit, particularly in its ride and refinement, with just over 200bhp. The Rover V8 produced no more power, unless modified.
I tried a 3.7, but felt that at 280 bhp it was a step too far, very much in the way the AC Cobra with its big V8 gave the impression that it wanted to bite if you relax for a moment. Fine if you want to drive on the edge at all times.
The Aero Plus 8 has, as mentioned, 367 bhp, but it is well matched to the chassis. Like its predecessor, it can bite, but doesn't seem to want to do so. So unless driven in an spirited manner it is an easy drive.
I'm certain Mrs A would be captivated.....if you let her try it.