I'm sure I've missed them, but I haven't really seen too many posts about Italo trains vs. Trenitalia.
This might not be the spot to do it, but I thought I'd post my opinion as many people have train questions and most seem to be focused on Trenitalia.
Last year we used Trenitalia, and just yesterday got back from a trip using Italo.
Verdict: Italo! Much easier website to use, could buy tickets farther in advance than the other, tickets were slightly cheaper, comfy lounges to sit in at the various stations with helpful staff, great shiny new trains, free wifi.
We were on basic lines using the same stations, so I can't comment on various "odd" stations. But the Rome Tiburtina was just as convenient for us as Termini.