I’m there with you. Have about 5 legendaries I believe, maybe 10-15 troops at level 15.
Pre patch, the main reason to get to 15 was to level up your Kingdom. With that gone, stopping at a lower level is very viable. It doesn’t cost many souls to level up to 8 or 10. (Does anyone have a levelling up chart to actually put a number to this?)
But the later levels are 300+ souls per level, for minimal gain. The total stat difference between a level 10 and a level 15 wouldn’t be that much I don’t believe (gut feel, no facts or anything to back it up). The only troop that I think really makes a difference are ones that have: 1) aoe effects based on magic, where a 1 stat gain in magic means a big difference, 2) gem creation (Acolyte, Siren, Borer). If you miss with gem creation, you give your opponent a 4/5 of a kind usually and it really backfires. Other than that, I can’t think of an instance where the stats would make that big of a difference.
Personally, I’m stopping at level 10 now leveling up troops. This way, when you play arena, if you have all the troops at level 10 you can purchase them for 1 gem, and get a bunch of souls (can someone provide numbers for ultra rare, rare, and common disenchant? I know common is a measly 5 souls).
I think the only way you can test a team is to actually play it. I’ve asked for a lot of advice on teams and there’s a big difference between an effective team, a fast team, and a ‘fun’ team (fun being different to everyone).
If you want to post up what you have people can put their input towards it.