3rd Party SMS with Gear S

Hello everyone! I'm new here :)

I had a question before purchasing the Gear S... I have a Galaxy S5 and I use Textra for my SMS app and I love it. I was wondering if the Texting feature on the Gear S can go though Textra or will it make me use the Default SMS app that same with my S5?

If it does require me to use the default app. Can I install Fleksy Messenger like I did on my old Gear 2 to replace the default SMS app on the Gear S?

Thanks :)