Volpunter thank you for finding the time to reply. I totally understand your sentiments about needing to understand the nuts and bolts of a trading platform - I used to be the test and documentation manager for the Gas and Power trading system of an oil major, who had twenty odd developers on their inhouse trading system. So I know about "features" in software!!
But I am not a good programmer and have been struggling with C# in OEC and having looked at the back data available in Open eCry decided that there isn't going to be enough to back test in any meaningful way, so it is best to abandon this path. So I am in the process of opening an account with Trade Station (which I know doesn't cater for exchange based spreads).
Quite simply I have some ideas which look okayish on Esignal (and now on OEC's charts) and I want to try them out in a more rigorous manner. I also have heard that it is likely that I will be unable to get to the bottom of exactly Tradestation will be doing when it back tests and so I will need to treat the results with suspicion.
I guess that what I will do if Tradestation suggest that my ideas are a goer is run them on either (one or more of) OEC's, Trade Station or Easyscreens simulation environment live, before venturing some single lots under a very close eye for a few months. This will no doubt result in expensive lessons. And it may well mean that I will then come around to your position. But at this moment I want to concentrate on getting a workable algo and not the platform.
I would be very grateful for your comments and pointers on implementation and the pitfalls of off-the-shelf platforms, if you are willing, when I am a bit further down the line.