Looks like there are TWO versions of the Keeppower 26650 with 5200 mAh listed capacity. At least HKJ has two recent tests, dated 6/22 and 7/12. One is listed as a IMR cell by Keeppower (the high current version) and the other is not specified.
IMR Test/Review of Keeppower IMR26650 5200mAh (Black) 2014
Not Listed Test/Review of Keeppower 26650 5200mAh (Black) 2014
Based on curves through the maximum draw of the non-IMR cells the performances of both are very similar but there are minor differences. As HKJ says in his ending comment though the IMRs are not really super high current cells.