I would believe that any amount of vacuum would be better that none at all. These food vacuum devices will pull a good vacuum, BUT if the volatile gases are sucked into the vacuum pump one stands the chance of destroying the internal pump mechanisms then nothing would happen. For $6.00 though I believe you just might be able to answer your own question.
The vacuum would help in the drying process and you could also assist in keeping the moisture from returning into the wood tissues IF you completely cover the blank in a drying crystal such as silica gel. This material is used by people drying flowers, etc. and is available at many good hobby supply houses. Also, call your local florist to see if they might have a source for the gel in larger quantities than the hobby houses. BTW, the stuff is not real cheap and you can dry it out by warming it on a cookie sheet. Just don't overheat it to much.
The problem ins using a vacuum is that the off-gases are quite destructive and will actually 'boil' like water on the stove. I usually pull a vacuum to just prior to the 'boiling' point and hold for a bit, then re-pull more vacuum as the gases fill the container. Works quite well for me BUT it is rather time consuming. Pre-drilling or turning down helps in the process as well. Just allow room to drill to final size or continue to turn to size.
