Congrats! Hopefully those three ×10 didn’t take away a lot of gems, at least for any future ‘wants’. As you say, it’s all fine as long as you like it, most of all. Any spent will be worth if it was enough to pull. But this Sync Pair sure has its good things as well!
Eruption is a really fun move to spam on an AoE unit, I myself would like to pull one some day (I would also complete the Johto starters trio with him as I already have Feraligatr and Meganium). Emboar and Infernape are focused on ST, but Typhlosion does his job well. Make sure to keep it healthy enough, though, or at least take advantage of it until you have accomplished everything you would like from him in a battle, especially in co-op, as other Pairs will be more consistent in the long run when it comes to dealing damage.
So far I don’t intend to spend gems on this one since I aim to get Leaf and Eevee at 5/5 and make their Sync Move the most useful as possible. Maybe if I’m lucky soon enough and still have a lot of gems, but I’m also interested on saving for Serena and some good Fairy-type Striker (probably Diantha & Gardevoir), plus I’m already very happy with my own Hilda, which I failed at the first time but finally got her while being rated-up last Christmas. We’ll see.
Feel proud and enjoy Golden Boy! Haha