As a user of the IQ line, I will pass on to you my thoughts. The official line from by dealers and Phase One is yes.
I agree that in very certain conditions, low ambient lighting, and with a ND 0.6 to 0.8 you may be able to wait through all the screen blooming to see if your tilt adjustment has made any effect.
Even in these conditions, with Live View on, you are talking about a pretty long wait from normal view to 100% view as the screen adjusts and blooms in and out, then if you move around the screen each time you move the screen will bloom for a few seconds then attempt to settle down.
All this time you are running down the battery pretty fast. The amount of time it takes IMO to check on average would be between 5x to 8x longer than trying to do the same thing with a DSLR CMOS liveview setup.
As a tech camera user, who uses tilt a lot, my solution is to make a setting, then check the back after the shot. You can get a lot more done this way and don't have to worry about waiting on the screen to settle down each time. This takes full advantage of the IQ screen's amazing resolution where as Live view does not.
One note, the latest firmware to the older IQ's allows you to have a B&W view as the new IQ's do and the old P65+ did. This may help a bit in the Live View viewing as the blooming will possibly be easier to work through.
One other note, in my experience you will spend a lot more time futzing with the ND filter, forgetting to set the shutter to wide open or back, and trying to shade the screen to see it (all working with Live View). Where as by taking the shot and previewing it you can get a lot more done. Live View on the IQ in any amount of normal outdoor lighting is pretty much a no go for me. Even with a 1.2ND on the screen still has a huge amount of blooming and each time you get this, it takes several seconds to settle back down.
Dealer demo, would be a great idea as this is something that everyone has a different opinion on. Also there are some write ups on this site about the new Cambo ground glass offering, written by Don Libby. From his reviews it seems like a great alternative to the Live View option. Cambo has a magnification setup that allows you to see the details enough to judge focus even with wide angles.
Paul Caldwell