Yea the time of the 9X radios are gone now, the Taranis is the new king. You don't need to install new boards and parts are available from a few different places now. There are a few new Taranis models out this year (2019 models) that add a bunch of new protocol features as well if you are still using 2.4ghz. Works with the multimodules too of course, both the serial and ppm versions. If you need to replace the gimbals then absolutely the hall effect gimbals are probably the best in the game for the price. However I'm pretty sure they are 3.3V so you will need to work that out. There are a few guides online but it might just be a good option to upgrade at once instead of cutting the gimbals up.
I would be super careful on the Jumper thing right now. From what I've been told the internals are a QX7 clone and FRSky is not to happy with the clone. Since they have paid devs on the OpenTX team and they also pay the team as a whole for supported features I highly doubt the OpenTX team can or will support them. Also after looking at the Github it seems they are pretty dead already. Since you have to purchase the 4n1 anyways (it isn't internal) why not just use a X9D/QX7/Xlite? If it were me I would get the X9D and use the Visaton BF32 speaker in it to get a nice sound on it. The print is on thingiverse for it and it is an easy install.