Efficiency of SST-90 at low drive current?

Hi,
i just saw the good deal on sst-90 leds at 4sevens and i was thinking about getting one maybe to replace a p7.
however, i don't want to change the driver, so the max drive current would be around 2.5 Amps, mostly less for low + med mode.
How much output would an sst90 produce at this level? propably the led will be pretty bored at that level, but for the price i won't get an sst-50...
how would the beam look? I'd like a nice hotspot with a floody area around...should be not a problem i think, how about the p7 reflector? can i keep it?

Thanks

should work great, i get an hour outta mine at the same current on an AW18650. should be somewhere between 500-900 lumens depending on your bin. and its big beautiful flood for me i love it! enough run-time, not too much heat, and lotso lumens

White LED lumen testing - Post #336

tl

Hmm sounds really good to me..think i will need to order one..or maybe two... and retire a p7