The medium format industry is in turmoil, perhaps that is what your lab manager friend was referring to. Yes, many of the major MF players have either died off or gotten out of the business during the transition to digital, but this always happens during major industry changes.
Personally, I wouldn't worry too much about folks like Phase surviving--I think the kind of image quality delivered by medium format backs will be in demand for a long time to come, and Phase (among others) will be there to satisfy that need.
In the end, though, since no one has crystal ball, you'll need to decide for yourself how much risk you feel is there.
As for image quality, I picked up a P45+ for exactly this reason. Here is a photograph of a 48" x 144" 4-stitch panorama, done with a regular P45.
In this print, you can easily see individual branches and twigs on the trees on the island--the Phase will definitely deliver the details for you versus the E1 (as will the 6x17, for that matter).
I think at this point it will come down to which best fits your budget, and ultimately which is your preferred way of working?
Let us know which way you decide to go,