Using MzS 360, no problems at all with uptime. The only problem I had porting was from Arc2 to Anarki Arc2.
For persistence you can probably get a lot of mileage out of making some small changes to the news.arc model layer. I found making changes when necessary was really trivial.
As for advice, I think you should not worry about when/if Arc3 is going out, and just proceed.
Good to hear about MzS 360, that's the package that installed on my local Ubuntu 7.10 system.
I just installed it on an older Ubuntu server that I'll be using for production and got 352, so that should be pretty safe given that's what pg is using.