I think you’d be hard pressed to find someone who chose to sell via an auction house and doesn’t regret it.
I sold a coin with SB last year, and I have no regrets about that sale. I made a decent amount and they made a decent amount.
Even though their commission structure (for loaded coins) is unethical in a general sense, it was reasonable in that case. I was lucky.
And for unloaded / unfunded / low denomination coins, I think the structure is fine since it works like any other percent-based commission system.