The TH9 and the G3 are about the same size.
I have a G2 and a G2C. They are both great guns (almost identical), and are my EDC guns.
I have no problems with the trigger, or any feed issues, and I consider them both very reliable.
I am looking to get a TH9C (C for compact).
The TH9C is about the same size as the G2C, but it has a hammer, and a decocker.
The TH9C comes with both a 13-round AND a 17-round magazine.
G2(C) trigger takes some getting used to. The trigger safety and the way it releases and how much farther back the wall is would be the difference. If you can find a friend or a range (when open again) for rentals would be the best bet. G2(C) and G2S are plentiful here the G3 showed up for like 2 weeks then the panic buying took them out. I haven't seen a TH9 or a TX 22 locally anywhere.
I have both the 809 and 809c, the predecessors to the TH9 and TH9c. I’m very happy with them both, with the 809c as one of my favorite EDC guns!
It only has the left side safety/decocker whereas the 809/TH9 is ambidextrous.
I got them on GunBroker; the 809 came complete in original hard case with 3 mags- it was in pristine condition! I think I got it for $210-215.
The 809c was originally an Israeli import as the logo on the slide was RETA- at the time the Israeli importer for Taurus. Stole it for $150 on GunBroker.
Avi Mor (Israeli firearms guru) did a full review of the 809c- and was very impressed with it.
His review is somewhere online.
(Gun Mag Warehouse had the new Taurus 809c
magazines for about $20)