ahh... sounds good.

I am running close to the same setup as you. Flat foam blades, super skids, a dual tail, training gear, extra flybar weights. I was running plasti blades, but I wanted to try out these foam blades, and I just haven't switched them off because they have been working well for me. I am also running an 8T pinion. I get about 12 min flight time on the stock pack, and put back in about 720mAh with the balancer balancing while I am charing (so probably about 660mAh is what I actually put back in).

maybe that progression of more weight meaning shorter time is what is going on =)

If you have a way to measure how much mAh is going back into your pack, you could also check that too.

There is also a small chance it could have something to do with your tail motor failing and drawing more current or something. That stock tail motor can draw up to 6.5A in a stall, and my whole setup runs on average about 4A, so an extra amp or two from the tail motor could decrase flight times quite a bit.

Anyways, I hope you get 'er figured out =) Good luck!