Hello, I currently have a license for Eset Smart Security with built in firewall and it's very good. Using this license I can 'downgrade' to Eset AV and then combine it with Comodo firewall, my question is this, which would be the most reliable/secure setup? A combination of both or just sticking with the Eset security suite? I suppose in other words what I'm asking is, how do the 2 firewall only aspects compare? Thanks in advance.
You don't need two firewalls. Use AV + Firewall. Or AV with an integrated Firewall. Not waste resources + more configuration always (or mostly) ends up with security problems. But both together is mostly problematically and I bet you're behind a NAT anyway so the GUI stuff is more to fine control several aspects. Nothing much speaks against to use Eset's own if you have the license. To much is overkill and also remember the resources, you should never wasting them (even if you're on a 'hyper-machine').
In the past ESS keys were usable in EAV (but not vice versa). But i would stick with ESS and not EAV+Comodo except you have issues but that can be solved with support. Cheers.
Eset's firewall in Smart Security has an IPS. As far as I know of, Comodo does not. It did have IDS/IPS many moons ago but then they eliminated it.
If by IPS you mean Intrusion Prevention System then Comodo has it and it's one of (if not the very) best.
Probably ESET av/Comodo fw I would go with ESET full though for the sake of peace of mind, Comodo can be a pain. Besides you can harden ESET at will, just search their forums for help.