EPTIn my PvZ 3-wg expo there's always been some intrinsic problem in scouting after the first lings are out. I'm forced to wait until my hallucinated phoenix/obs are out before I find out exactly what the zerg is doing, and during this period, you're in risk of dying to all-ins (i.e. speedling/baneling or roach/speedling all-ins) or going for a sub-optimal tech path against the zerg's build.
Pre-1.3.3, going the hallucinated phoenix route is much faster than robo after expansion as hallucination research time is relatively quick and phoenix are naturally faster scouts than obs. I think most people would agree that hallucination is much better scout. After 1.3.3, warpgates delay your hallucination by an additional 20 secs, which even further delays your scouting info.
After 1.3.3, I'm proposing that hallucination before warpgate might be a good option since sentries have the exact same build time via gateways and warpgates, so there will be little-no delay in the availability of sentries for defense. In a 3 wg expand, players opt for sentry heavy composition anyways. After thoroughly scouting your opponent with your first phoenix, there should be adequate time to respond to the zerg - whether he's playing aggressively/economic and his tech path.
Going warpgate after hallucination should have very little affect on your build unless you try to pressure after your 3 gates are finished - but I find heavy pressure from 3 gate to be extremely risky. Having your warpgate done after hallucination should still give you ample time for a timing push and the same number of units (assuming your produced mostly sentries pre-warpgate).
I have yet to try this but I think it will be a safer choice. I've started laddering a bit on a new EU account and am currently mid-master's but climbing steadily into high-masters as I have time to put in more games. I'll try to get some replays up.
