Need IIS Recommendations

[ChiefPeon]

Not sure if this is the right section for this or not, but looking for recommendations (NOTE: this is not my area of expertise). Recently took over a network that currently has 4 (maybe 5) IIS installations. I've always lived by the thought that less is more meaning that I've tried to run everything on a single IIS implementation to reduce the update/management overhead and the security footprint. So my question is...which is better? Less or more? Pros/cons for either way?

 

Background: we only allow OWA traffic inbound from the outside. All other IIS traffic is internal. If I recall correctly we have OWA, 3 or 4 DB applications that are utilizing IIS as a frontend, and a management software. So, we currently have IIS installed on the Exchange server, IIS installed on 2 SQL servers, IIS installed on a backup server, and one other one if I recall correctly.

I know (or at least I think) that 2 IIS servers will need to be running. We've recently upgraded a DB application that requires .NET 4.5 and an older DB application that was running on the same IIS server requires .NET 3.5.

Any and all input is appreciated!