Hi there, I fly a lot of HEMS work in the UK on 902s with both 206 and 207 engines although I haven't flown London HEMS Ops.
I have never yet had to use more than 100% torque AEO on HEMS ops to clear even very awkward and congested sites (even close to MAUM and well outside 30 degs of the wind). This may be in part to the normally temperate conditions in the UK.
The only time I've gone into 5 min power is on offshore ops where we were operating up to the 6900lb limits for external loads. Even then it is fairly unusual. I did once see transients (red!!) with a load underneath but only for a short time and it was down to my harsh handling!!
On the whole the 902 has a large AEO power margin in UK ops.
Hope this helps!!