Yes, always compare with rented dedicated, and only go with colo if it makes sense. I did this analysis last year and rented won big time. Never looked back since.
Main points in favor of rented dedicated servers:
- Much cheaper in my business case (5-10 TB/month by server, only a few high CPU requirements) most dedicated come with bandwidth included
- No need to take care of the hardware in case of failure (opening a ticket versus managing the whole process)
- Easier to switch machine if needs changes
- Scales faster (as quickly then 2-3 hours with decent automation tools, and virtualization)
- No switch, firewall, etc (IPMI should always be behind a firewall, never opened on the Internet)
- The upfront cost to buy a server was high, and monthly cost of dedicated was actually lower, due to the lack of competition in the colo sector in my area (Montreal, Canada), prices were (and still are) rising quickly, it was hard to predict the long-term costs
Maybe it is a Canada thing. I looked at some colos in the Toronto area a few back and found rental prices were about the same as bringing your own hardware. Didn't make sense. I was just looking for a home for some server hardware I have in my garage. Oh well.
Almost all the independant colo centers in Montreal have been bought out by big players with the corporate world in sight, not the small 1-2 servers market. So the prices skyrocketed.
The opposite is true for dedicated, since they have to compete with us-based players, and OVH got in the East Coast market big time. Prices are lowering.