I Like cells in series!
But, to address the XHP doughnut hole/cross I “think” that it was found that the (I don’t know what to call it) the interior diamond or maybe fluted shaped actually worked see WTS 4 Illumination Machines LUM 5-90 95mm x 62mm Diamond Text. Reflector *All Sold * Illumination Machines LUM 5-90 95mm x 62mm Diamond Text. Reflector the OP was sort of a close but no cigar type of concession. If you are going to go to this much trouble might as well get the reflector right!! 
Oh and the XHP 70 tints seem to be running cool, so a good choice of desirable tints (multiple NW for example) (not just what is cheap or left over).
Look at the X5/X6 group buy and take a look at the overwhelming demand for NW tints. In fact it seems that a choice of NW tints might pay off (it seems that folks actually have different preferences in this most desired of tint preferences).
I know that the tint thing sounds like a personal dig and that is not intended, but it does need to be said and admitted, that WAY TOO MANY manufactures seem to be chasing big lumen numbers and PUSH undesirable tints on us to suit their big marketing lumens numbers. Instead of supplying us with tints that don’t make us want to run out and swap the emitter of immediately, or not buy in the first place. A new cutting edge idea! a choice of NW tints, no other MFG is doing that (yet 
).
Again not a direct accusation but it is way too common “out there” and is easily found in “new and improved” lights ALL THE TIME, so lets head that one off right up front.
Thanks