So in like a couple of weeks I'm gonna start studying/practicing in my home lab these (and if there are others they are welcomed) firewalls / UTM.
What i really want to know is how they behave (as in performance), the kind of features they have (if they support VPNs and how many, ease of publishing rules, the amount of updates released by the vendor, etc.), your experience of this products versus commercial ones (like Cisco, Juniper, SonicWall, Fortinet, etc.). I'm a ISA / TMG guy but i must learn other alternatives since TMG isn't available right now (and it's phased out) and the recommended ones by Microsoft are way too much expensive ones for the clients i have (small/middle sized business).
oh also very important: most of the clients i have they publish OWA (exchange) via ISA / TMG, so this firewall must support this as well.