I have dove with both the TG-2 & the TG-4. The TG-2 I've done both with & without the housing, however the TG-4 has always been in the housing. I used the Olympus housings for both cameras & haven't had any unexplained issues with them. I like that the Olympus housing is clear, so I can easily see if the housing has a leak before I get too deep.
My setup is the housing attached to a double handled tray, with both handles having loc-line with Gobe 850 Wide lights attached, & also a cold shoe mount on the housing with a Gobe red filter light attached. I have used that same setup for both cameras & have loved the ease of use & the flexibility the Gobe lights give me. I enjoy fluorescent night diving, so the Gobe lights allow me to quickly switch out to the Nightsea heads & then I throw a yellow filter on the front of the camera housing.
After my mother killed her TG-1, I handed her down my TG-2 & housing & upgraded to the TG-4. Currently in the process of upgrading to Sola lights. I don't think you can go wrong with either housing, but I recommend the Olympus housing.
Attached is what my setup looks like & a pic I took in the Turks & Caicos last year.