Question Kunena 2.0.1 on Live Site - Type of Hosting

Hi all,

I'm getting prepped to move a test site from a test domain to a live site and will most likely build the site from the ground up rather than copying and pasting everything due to database fears. Feel free to comment on that if you would like as I haven't had the pleasure of doing so.

I'm also looking at running multiple test sites on subdomains in order to test major upgrades to Kunena/Jomsocial and whatever else I might want to add.

Now, here is the big question that I am simply unsure of. How much traffic is a lot of traffic for a server to handle? I hear people say "heavy" without defining what heavy is. I think I'm eventually looking at several hundred unique registered users to the site a day (obviously not all at once). However, concurrent users may reach above 100 at a time.

All this said, can a shared hosting plan deliver the performance I need or will it slow down? I'll be using hosting from sibername.com in case anyone wants to know. Server information pulled from the site for the technically inclined (running Linux + Cpanel):

Fedora-CR2-BASE
High Performance Dell PowerEdge Servers
Dual OC-48 Connections on Diverse Backbones
Cisco Routers Using BGP4 Protocol

What are general opinions on this hosting versus a VPS? I do realize there is a significant cost increase, but if that is something I need to look at, I would like to know now rather than 4 months down the road. The major component of this website will be Kunena though.