I have a mJ and have forwarded GV to it. Very reliable for the most part, but some callers have called the mJ number and the mJ phone didn't ring despite their hearing the ringing sound. Some destination numbers won't ring when called from mJ. These get fixed sometimes, amid reports that mJ has issues with certain local exchange companies who charge higher than mJ wants to pay for completing a call, and the two companies get into a p*ssing contest.
Nowadays, you might dial a regular-type-looking number but then the mJ robot says to prepay to complete calls to certain kinds of numbers including the one you just tried to call.
You can't spoof a GV number with your mJ, so if that's important you will have to use a computer or GV app to make the callee see your GV number; that's a way to work around the mJ pre-pay requirement, too.
Conclusion - mJ might be a good option for you, but issues do arise.