GV mobile + allows you to switch from multiple accounts. But the app itself is kind of buggy. Deleted it cause it just never worked right for me.
The Google voice app from the app store is the best quality and pushes text flawlessly. It just seriously lacks any real type of settings. I use this app for GV 100% of the time. Hasn't let me down yet, and I text and call a lot with it.
I also have GV Connect, it has almost all the settings possible and would probably be a great alternative to the app store version but, it has a MAJOR flaw. It just doesn't stay logged in and you have to log in(gmail & pass) everytime you open the app. I mainly just keep it installed just to change the GV settings instead of having to go to the browser.
So the combination of Google Voice app from the app store which works flawless, and GV Connect to change some settings every once in a while works great for me. I don't recommend GV Mobile + at all.