Will the EFI pump move enough air through it to disturb the fuel rail
pressure that's being delivered from the other pump,   I would say yes    
I'd bet that you have a 50-50 chance of being right :-)   Seriously, I'm not
so sure it would pump air well enough to overcome the 43 psi of pressure
that the other pump is putting in the rail.  I guess the only way to find
out it to do the experiment. I'm not completely sure that's what I want to
do anyway.   Yep, still trying to figure out how to fix my fuel transfer system.    What's it look like now?   
Remember the recent caution about copying a system 100%, or it becomes a new
system?  Well, guilty as charged.  My system is just like Tracy's, except
that I only have one return line to my feed tank.   I plumbed the wimpy
facet transfer pump into the same line that returns from the regulator.
That means the facet pump is trying to push against the return flow from the
regulator, and it's not doing too well.   Even at it's best, on the ground, with no other pumps on, the facet is slow.
In the air, fighting against one EFI pump's return flow, it takes a long
long time to see fuel moving.  With both EFI pumps on, I almost wonder if
fuel isn't going backwards into the non-feed tank anytime the facet wasn't
on because the check ball isn't perfect.  I added a one way valve to stop
this, and to stop the fuel from leveling itself between tanks when parked.

 
The obvious solution is to "simply" (NOT) add another hose to the feed tank.
Even if I go through all that hassle, I'm still stuck with the slow rate of
transfer of the facet.  It's probably still the best option, but I'm going
to investigate every other option before doing this.    Rusty