Comparing real trading costs on Deriv: how do spreads actually compare once you factor in rebates?

I’ve been trying to figure out if the rebates from GlobeGain actually make a meaningful difference when I’m comparing Deriv against other brokers. On paper the numbers look good, but I want to understand what my actual cost per trade really is.

I know that raw spreads don’t tell the full story. There’s commission if you’re using certain account types, rebates that vary based on volume, and then the market conditions affect everything anyway. It gets confusing fast.

What I’m trying to work out is a practical way to compare my real costs instead of just looking at what brokers advertise. Like if Deriv has a 1 pip spread on EUR/USD but gives me 0.3 pips back in rebates, versus another broker with 1.2 pips but no rebate, how do you actually calculate which one costs less when you’re doing maybe 20 to 50 trades per month?

Has anyone actually tracked this and seen whether rebates genuinely change which broker makes the most sense for your trading?