yeah... flagship model have the safest bet of getting updates (hopefully won't end up like XS, getting JB update almost the last one... )

but what i don't understand is all the diff variant of "flagship" model released...
Z, ZL, ZR and UL - high end model
SP - mid range
L, M, E - low end

is there a need to release so many diff variant of the flagship model? or does the ZR consider mid range cos of smaller screen size?

Actually Sony release too much.

Z, ZL = same, just one without water resistance. If already thinking of ZR release, the ZL is extra, lucky it look quite nice in actual.

ZR for people prefer smaller size, even it is only 4.6 but still can use 1080P screen, so I count this as middle-high.

SP - Mid range.

L, M, E - all low end, too many low end series.  (M mention as middle range, for me, sorry this is low end phone)

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UL is Japan only, a bit like ZL in worldwide, A is Japan also, similar as ZR. Actually I seen no point release specific slightly different / change name for Japan only.