Thanks all. Looks to be a pretty friendly forum this.
Mike- thanks or the welcome. Tax savings- the Zed for me simply going to be second/weekend car so I'm looking to keep things cheap(ish) as I'm looking to save for other things next year. I very nearly took out a pcp on a 2015 Nismo 370z a few months back but after a re-evaluation I'm going to be sensible- the AMG was a high tax bracket car but now I'm deciding to keep costs down- she will only be used for relaxing weekend drives and the occasional Nurburging blitz, 6-7k miles a year max.
Driven both the DE and HR engines- yes the HR is better but I don't know. Neither lump feels 'fast' to me, but they both sound tuneful, are torquey and have a nice wide powerband which is enough for me. Looking for a Cabrio as well as I miss open top fun from my old M3.... whenever its not raining, down it comes!
If anyone can convince me why I should put my hand in my pocket and get the HR, I'm all ears