I found it practical to use at least two GV numbers in one android phone with reasonable usability. I had purchased the Groove IP app for my primary GV number since it was proven to be the best solution for using GV with android phones. Then I installed SIPdroid and created an PBxes.org account for using a second GV account with PBxes.org. I then switched to csipsimple for this GV number since it can be integrated into the native dialer. In theory, I could run SIPdroid to register a third GV account then I can have three GV numbers to work in one cell phone but I haven't tested that yet.
I did found one issue initially: csipsimple no outgoing calls
I updated csipsimple to the latest version but that didn't help: it can receive incoming calls without any problems but can not make outgoing calls with its dialer. It typically drops calls in one second after the outgoing calls are dialed. I thought Groove IP and csipsimple could share the native dialer but apparently that is not the case. I needed to uncheck integration csipimple with android in its settings to make outgoing calls working again. Otherwise it would try to use the native dialer for outgoing calls and that was default to use Groove IP in my native dialer and that's why it failed.