Do you want someone looking over your shoulder? There are a variety of firms which will assign a broker to you that you can call and chat with. Lind-Waldock seemed nice with reasonable commissions. I wouldn't recommend Man. (Yeah, the irony is that Lind and Man are the same company)
If you don't want someone looking over you shoulder, try out the trading platform. At length. In general, they're terrible. Some are so terrible, that you're bound to make mistakes.
Man, for example, requires me to figure out the proper multiplier when I enter a price. Sometimes it's x10, sometimes x100. Sometimes it requires me to specify prices in 4ths or 8ths. For example, to buy corn at 342 1/2, I have to enter "3422" as the price.
Man also requires spread orders to be entered in the proper sequence, which varies per market. Some want sells listed first, some want buys.
When I place a spread order, Man has 3 radio buttons where I can select "buy" or "sell". If I select sell for each leg, and then sell for the whole thing, what happens? It turns out exactly the opposite as happens with IB when I select sell-sell-sell.
Anyway, there are major pitfalls here, and that's just the trading platform. Wait until you get an inverted spread fill, or they've computed the multiplier incorrectly. Wait until you find out that the wheat pit guy is awesome and gets you incredible fills, but the lumber pit guy gets you the worst fills you can imagine.
Do I sound bitter? Perhaps wiser for the experience. When IB picks up electronic grain and meat options at the end of this month, I'll likely be closing my Man account. I'd love to trade softs (coffee in particular), but it's just too dangerous.
As an example, I bought $625 worth of Fed Fund straddles. It showed up on my statement as $62,500 worth of straddles. On top of that, their accounting system counted all of those as shorts that were worth -$62,500. Net result, Man's accounting system showed I was $125,000 in the hole on $625 in straddles.
In their defense, their customer service has been great at fixing these issues. But, I didn't get a whole lot of sleep the night I got my statement showing I paid 100x more than I thought I did for some options! (Of course, had the fed lowered interest rates, I'd have been happy to collect my $12M in profits)
