DAX futures - spread vs cash?

This is a great question. I've been wondering about the spread costs myself, especially for shorter-term trades. Does anyone find that the futures spread is generally tighter than the bid-ask on an ETF, or does it vary a lot depending on liquidity?

One big thing to consider is the rolling cost with futures, especially if you're not planning to close out your position before expiry. That's a non-factor with a cash ETF, which can make a difference for holding periods.