The Samsung 1500's I have are INR, not IMR. Bought from FastTech "as is", obviously pulled from a pack because of fastening marks that I filed down.
Here's test results on a mod'ed XinTD C8 - XM-L2/U2, SinkPAD, 3.85A Nanjg driver, extra copper, 22 gauge silver tinned teflon coated wire, sanded/polished mating surfaces on the SinkPAD and top of pill. In order of results, 12 tests performed, all batteries are unprotected, freshly charged, first # is @start, 2nd # is @30 secs, in lumens:
Sanyo 2600 #1, 4.20v, 3.74A: 1190 - 1135
Pana 3400 #1, 4.19v, 3.56A: 1156 - 1111
Sam. 1500 #1, 4.19v, 3.85A: 1264 - 1213
Pana 2900 #1, 4.18v, 3.44A: 1128 - 1088
AW IMR 2000, 4.18v, 3.84A: 1203 - 1145
Sam. 2000 #1, 4.20v, 3.85A: 1258 - 1230
Pana PD #1, 4.19v, 3.85A: 1230 - 1183
Sanyo 2600 #2, 4.20v, 3.77A: 1190 - 1135
Sam. 1500 #2, 4.20v, 3.85A: 1237 - 1186
Pana 3400 #2, 4.18v, 3.54A: 1139 - 1094
Sam. 2000 #2, 4.20v, 3.85A: 1254 - 1227
Pana PD #2, 4.21v, 3.85A: 1244 - 1183
The "#1" and "#2" designates unique batteries because some tests were repeated on the same make/model. All tests had 3-5 minutes in between, accept the last which had a gap of 17 mins.
It does look like the winner is the Samsung INR 2000, better than the Samsung INR 1500 and Panasonic PD's. Of course this is only for the first 30 seconds...
So NightCrawl, I do believe you are correct here about the 1500 not being an improvement over the 2000. I think earlier tests I did contradicted that, but these tests were done now with more control (voltage and amp measurements, all batts off the charger, etc.).