Hi. I use DMA's radius manger/ billing server
for AAA my clients. I manage the Linux box
at the office but lately the power outages are
just too much that the UPS gives up before
power is back.

I am considering getting a VPS and have
the server on it. Is this a wise Idea? They
say I get full root access but to what extent?
Since i need to install radius server and get
the NIC mac add that doesn't change.

I came accross this http://www.webkeepers.com/vps/index.html
Anyone with experience with VPS?

If you are dealing frequently with long term outages which a UPS does not accomodate, then perhaps you should consider a Backup Generator with a Bypass switch to your panel.

Check out IX for VPS hosting. They got 24/7 support for Windows and Linux Hosting and they also offer a free trial. I use them for web hosting and I'm really pleased so far ( 3 month now ).

You might check out this too: https://www.fitvps.com/

Anyone with experience with VPS?

Sort of - it's how we run a lot of our MT routers, Linux servers, web servers and even Windows servers. All on our own ESXi 4 based dedicated server at OVH. Not had a hitch yet. (Except when our office forgot to pay the bill once). They soon learnt not to do that again!