Is that a deal-breaker? For most people, probably not. For most people, even a vague promise of a "quick" Android upgrade is more than enough. But for the type of people who are going to be interested in these particular phones — many of whom are bound to be Android enthusiasts — the ambiguity of the devices' upgrade situation is certainly something to consider.
If you want a guarantee of immediate OS upgrades, unlocked Nexus devices remainthe sole option for that explicit assurance. The Google Play Edition phones should get upgrades "quickly," relatively speaking — but the process is unclear and untested, and what "quickly" means is still open to interpretation.
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