Does a vacuum breaker flush valve deliver enough water at once to cause a standard toilet (or a low flow toilet) to flush if it is supplied via a 1/2" water line. My observations in public restrooms suggest that the feed line needs to be bigger.
A commercial flushometer valve plumbed with a 1" supply line is very different than a tank slowly filled with a 1/2" supply line.
The 1" supply flushes in 3 to 7 seconds
The 1/2" supply may take 120 seconds to refill.
Imagine being in the shower when somebody flushes the toilet.
All of the cold would be gone, all you would have left is scalding hot water.
If you want to go with the commercial flushometer,
1) Change your water meter to a larger size and upgrade your water service to 1.5"
Then Run 1-1/2" to your bathroom set, and stub out with 1" using a 1-1/2" x 1" tee.
It should only run you a few thousand dollars.
Skimp on that, and be like all the homeowners before you that wish they hadn't tried.