Allow me to inject some sanity into this thread. When trading Eurex, Mirus charges you a commission charge in US dollars (2.10 round trip) and exchange fee in Euros. IB's unbundled rate is all euros, currently 2.62 Euros round trip for FESX for example. If you convert everything to the same currency, the round trip commissions for FESX when EUR/USD is at 1.40 it looks like this:
Mirus: $2.856 USD
IB: $3.668 USD
Mirus clearly wins hands down. Basically, when the Euro is high against the Dollar, Mirus has better rates. If the Euro were to approach parity with the Dollar, IB would start to look attractive. And if you trade ES, IB's unbundled rate will charge you 4.70 a round trip, while Mirus will charge you 4.40. If you're a low volume trader, Mirus is clearly the way to go.
And someone else already said it, but there is more to a broker than rates. I've traded Eurex with both, and Mirus is 10 times better. NinjaTrader is an excellent platform, the zenfire feed is in a whole different league (way above) IB's filtered feed, and with Mirus you don't have to pay those rediculous order cancellation fees on Eurex like you do with IB.
Mirus is an awesome broker. I have accounts with both but I am hating IB more and more each day. The only thing I wish Mirus had was access to the Asian markets, but that's a zenfire thing, not a Mirus thing, so hopefully zenfire will expand into Asia someday so I can consolidate my accounts.