Walter,
You'll find the ES is the 'slow and steady' contract vs. the ER2. You won't find as many wild whipsaws and spikes as you might with the ER2 and maybe even the YM. I think it's a function of the massive liquidity and all the pro's there - humans and computers. It's much too efficient to see wild, random spikes consistently.
Of course, trading size is not an issue either which is also attractive.
So if you are after an index contract that is less 'spikey' the ES is a good option and probably the best one. As a scalper, you can easily load up on the number of contracts trading w/o worrying about setting off any red flags or anything.
One note - when you watch the contract and esp in simulation, assume in order for you to exit a position that price must trade THROUGH your price level and hit the next level to get filled. Example - if you are trying to exit a winner at 1500, price will need to touch 1500.25 in order for you to safely assume you get your exit price. NEVER assume that if price touched your level that you are out. Unless it's an MIT order of course.
