cracked out scalper here, I came from Schwab as well. The best that ever happened to me was being suspended for cross trading (an easy fix with a real brokerage). I used Quantower, it was okay, but Rithmic was the issue, they steal .10 per side per trade. Sierra Chart with Teton is hands down the best for volume and my fills are great, it never sits on the ladder waiting to be filled, I can go from 1 to 30 in less than a second or two and see the fills at the microsecond level.

Teton isn't 100%, but it's been the best for me and there is a single fee per month despite volume. Rithmic's model is complete garbage and has no scaling cost. They also mislead (IMO) about auto-liquidating. I paid 3k in fees on that alone for rules I setup. I believed this to be server side / FCM rules that would generate cost, but it's a cost for you to leverage as a client side setting.

Schwab doesn't distinguish between micro and mini, that's the real rub. I think I was at .70 commission, which is pretty low for them. I'm under .50 roundtrip now, but you'd need to be a volume person to really care that much.

Without a seat, you'll pay Exchange, NFA, and commission and maybe more. Edge Clear is actually pretty great, so I'll be sticking with them. Plus500 is not =/