I would not EVER use one of those regularly - it only builds vacuum, not a build and release action. So the more you hand pump the harder and harder it sucks. You can easily ruin teats and cause mastitis and rupture blood vessels and .....
Vacuum needs to have a cycle to it, on-off-on-off, etc.
I ended up buying a surge
bucket milker and installing an old
dairy vacuum pump and running tubing to my stanchion for my 42" jersey/guernsey. Total cost was maybe $500 and a ton of work running electric and figuring out how to regulate pressure, etc, but it was well worth it. If you have more $$ than buying a smaller, portable, quiet system would be ideal.
GL!