You won't lose it, but it becomes a lot messier for a minority SH. I expect RMS will end up with their 90% and will mop the rest up under compulsory acquisition. Those that don't accept will get the same terms - just a lot later than the rest.
This isn't advice, but there's no downside in accepting (if you want RMS shares) because even if another offer eventuates, you will still benefit from that.
You have until the 18/08 to accept.
Here's the page in the bidders stmt that talks about it
MGV Price at posting:
34.0¢ Sentiment: Buy Disclosure: Held