Traders' Roundtable

I'm new to the futures. This forum is by far the best source of info on the Net I could find so far. I have many questions, but let me just start with one.

What are the disadvantages (if any) of e-minis as opposed to pit traded futures? The slippage is supposed to be none (is that right?), the liquidity is great, comissions are low $4.80 per contract at IB, and finer granularity would allow one to diversify with smaller capital. What's the catch ?

The spread is 2.5 times greater than the big contract. Even with zero slippage you lose a minimum of a 1/2 point per trade plus commissions which are four to five times greater.

I can see that the tick is indeed 2.5 times wider for ES then SP (0.25 vs. 0.5 on a five times smaller contract). Not so for Nasdaq - the tick for full contract is 0.5 - exactly five times of e-mini Nasdaq 100. Question: is there often more slippage then 1 tick in E-mini trading ?

sometimes, heres a sample of my actual slippage, each number is for a round trip (buy/sell) trade.

-0.25
-0.25
0
-0.25
-0.5
0.5
0
-0.25
0.5
-0.5
0
0.25
0
-0.75
0
-0.25
0
-0.25
0
-0.5
0
0
0
0

I recall reading somewhere that mini contracts at times have greater volatility than the corresponding big contracts. The implication was that big traders can jerk around the mini markets to the disadvantage of small traders. But I haven't been able to track down a concrete reference that backs up my recollection.

This thread discussed the spread size and commissions as disadvantages. Does anyone have personal experience or links to sources that discuss other pros and cons? Is there any liquidity problem with mini contracts?

guys in the pit wont care executing one lot of S&P, so you'd be better of trading emini, if you wanna trade S&P