A big decision. Good to seek advice (even from the sometimes jaded membership of pprune!). If it were me, I'd look at a visit to 'shadow' an AT (where are they now? Waddo?) and maybe a chat with a few other EngOs to get an idea of the 'view from over the fence'.
Preparing for either will involve the same sort of work (see the commissioning club for advice - assuming current station has one).
Choose a preferred option - go for it and if knocked back, think about if option 2 is better than waiting for another go at option 1. Some research into slots/chances of success may swing your decision one way or another (future for the AT role?)
Having been aircrew and gone commissioned, both careers are challenging and rewarding so make the most of what you end up with and you won't regret it.
You'll need a thick skin in the meantime - suspect the tea-bar pprune readers will put your ex-Puma and current Lincolnshire role together to blow your cover
Remember, the gripers and wingers will still be wallowing in their misery when you are long gone and enjoying your next role. Good luck.