The issue is driving them !
The SST 50 is hard to drive well @ 4.2v ...
THe SST 90 is almost impossible to drive well @ 4.2v
At 8.4v its a different story ,
Anything the SST 50 can do , the XM-L can do , making the SST 50 redundant ..
The SST 90 is expensive , needs to be driven hard , Im sure they have there fanboys , but for mods and DIY there just not worth it , the XM-L is choice !
When $$ count , the XM-L cant be beat ...
Is the SST 50 like $35
The SST 90 like $70 or something
The XM-L can be at your door for $9
I have a SST 50 P60 drop in , and it can only compete with the samsung 30A battery @ 4.35v , the slight voltage increase = about 200Lumen
With a fresh 4.2v it will do about 500L and with a fresh 4.35v it will do 700L , I think I need to add some 7135 chips to that driver one day .
But the thing is , a lowly driven XM-L will do 700L with a regular 4.2v cell ..
Im sure we all dream of monster output , I even built myself a Dual XM-L U2 P60 drop in , but I just cant drive that drop in hard enough , yeah , more driver mods needed .