The throttle plates are affected on most all hat style injectors. Two things to consider, alot of applications using these such as tad and tafc idle at 2000 which is a big enough leak it's not as bad and most all of the hats I've worked on took a pretty stout spring to keep it on the stop. So the smaller the combo/idle the worse this could be.
Good luck.

With my four blade hat I have return springs on both ends of the throttle shaft, also adjustable air bleeds just above the blower in the hat helped with idle stability.

I currently run a 441 sbc with a 8-71 high helix and use the same 2 1000 cfm APD carbs that were on my NA sbc. At 14.5% under driven it makes 5-6 psi and 989hp at 9% under driven it makes 7-8psi and 1037hp and at 6% under driven it makes 9-10 psi and 1148hp. The carbs work great on my deal. I do not have to change jets if I change pulleys, just change the pulley and go. I have very little blower surge, as in most people do not know it has a blower until I raise the front end, since it does not stick up through my hood. I thought I would eventually switch it over to injection once I got it running well, but at this point I am staying with the carbs.