I used a penimaster pro for almost a year. Newbie gains were fast and I believe I got almost 1/2 Inch from there (Erect length). After that it was slow going and I gave up after the year. I think overall I gained almost 3/4 Inch but since I've stopped I've lost some but haven't measured in a while.
If you are a newbie I am sure you can make gains with the phallosan but I think any newbie can gain a half Inch with most any method if done for a few months. I have a phallosan and tried to use it for 4-6 hrs a day 4-5 days a week for a few months and didn't see any additional gains. But also had already gained about .75 inches in prior years from a variety of PE methods. I still use the phallosan intermittently as ADS to maintain length. It is pricey though, especially replacement sleeves which can tear easily