[DUCKVILLELOL]

Originally Posted by pezzaperry

sigh its not safe to expand at all if you're doing a phoenix mirror. You have exactly the same tech paths and unit count, where is your advantage coming from? The only advantage you have is phoenix rally time, that's not enough to justify 4 additional zealots within your opponent's army. If you want to try phoenix mirror against me that's fine, I will show you why you can't expand unless behind a forge. The timing will hit as your nexus finishes and you will be down 400 minerals worth of units, lose the fight and ultimately the game. Or else you can sit on your ramp and lose 400 minerals as he kills your nexus for free and takes his own expansion.

edit:

I've had so much discussion time with NA grandmaster phoenix users on this subject, it's not even debatable, nobody in high level play will take an expansion in a Stargate mirror unless you have either A) Gained some ground in the early game, or, B) Gotten a forge and cannons up before his push hits.

"Where is your advantage coming from" - where is the disadvantage? If you have the same units... there is no disadvantage, it's fine to take the expo. I'll agree, yes certainly if you see that your opponent doesn't take theirs straight away too you'll obviously need to get some more expenditure going in your units instead of continuing to make probes (and yes, you'll likely need to make a small investment of 450 in forge/2 cannons) but this in no way is something that'll cause you to "ultimately" lose the game. If you are properly using your Phoenix and being active with them, you really shouldn't be blind-sided by someone who just attempts to 1 base bust. If it means losing 1 nix to scout what's coming, so be it. Better 1 nix dead than a game lost.

I know it sounds stupid but so many people even at a high level really don't understand how to play this particular style. You take the expo fast, put down a couple of cannons, and you'll be fine. On a map like Ohana sure you'll have a little more to contend with because of the second opening, but in the end it's not a big deal. Have a look at some of the replays in the link I posted before to see what I'm talking about.

As shieldz has pointed out though to directly answer the OP - you just need to stay ahead in nix count and you'll be fine.