The thing that keeps me from using them more is the 2.9% they take up front. That 2.9% is gone, immediately and forever, no matter what you wind up winning or losing with that money. That is way too much for the way I bet.
Say you place three bets, one at Mansion, one at Matchbook, and one at Pinnacle. Each book receives $1,000.00, each bet is at +100, and all three win. You withdraw the winnings immediately. Here's what happens:
Mansion
Deposit: $1,000.00
Cut: -$0.00
Bet: $1,000.00
Win: $1,000.00
Commission: -$10.00
New Balance: $1,990.00
Withdrawal Fee: -$0.00
Cash Out With: $1,990.00
Matchbook
Deposit: $1,000.00
Cut: -$29.00
Bet: $971.00
Win: $971.00
Commisson: -$0.00
New Balance: $1,942.00
Withdrawal Fee: -$0.00
Cash Out With : $1,942.00
Pinnacle
Deposit: $1,000.00
Cut: -$0.00
Bet: $1,000.00
Win: $1,000.00
Commission: -$0.00
New Balance: $2,000.00
Withdrawal Fee: -$15.00
Cash Out With: $1,985.00
Matchbook is the clear loser here. Their odds have to be significantly (several cents) better than anywhere else for me to even consider depositing. And even when I do, losing that 2.9% immediately never feels good. Even though it is put toward "Commission Credits", you're still under the best case scenario paying 2% instead of Mansion's 1%.
If you're already posted up there, have some commission credits under your belt, and see a great price, then sure, it can make sense. But if you like to selectively bet and frequently withdraw (like me), it just doesn't work.
GL