It does seem quite a personal thing as for me it was a big problem on my R.
A lean engine will run hotter but TBH I noticed no difference on mine once Hilltop'd Redrick.
Those air deflectors look really good Paul and at that price it'd be silly not to try them - I actually prefer the looks to my Wings panels as they are less obtrusive and they're certainly a big improvement on the panels that came out when the SA was launched which I thought looked truly grim.
My experience (in hot weather) was that the warm seat/inside thigh was never an issue. All the heat was felt just above and below my knee. On the move I could feel it but it wasn't an issue. Slow traffic it was very noticeable but bearable. Stop/start/filtering city traffic was grim.
The Wings panels alone made a small but not significant improvement. The panels coupled with the extensive heat reflective matting supplied with the panels were a very big improvement (they run from the back of the tank to the rear seat latch). They got tatty after a while from frequent removal so I ordered some matting off eBay which is a lot thicker and this has all but sorted the issue completely. This was 'tested' in Spain last year, both in busy cities along with a fair bit of slow off-roading, I'm very pleased. Quite why the matting under the seat should make a difference around my leg god only knows
Andres