There are more qualified people here than me to comment, but my initial reaction is that if you are scalping and use limits orders, getting filled might not go as smoothly as your simulated tests, meaning, many times you might not be filled.
Also, I do not see what your platform has to do with limit orders, or even your broker for that matter. Your order is going to be at the exchange, and given that they are limit orders to enter, you will be waiting in a queue there.
Perhaps what you read is that the SIM trading of limit orders on Tradestation doesn't work too well because it gives generous fills. (ie. assumes that you always get filled as long as price touches just once).
Where you are in the queue depends on when you put your order in. So if you see price hit your level, and then you decide to put an order to get in, you simply might not get any fills at that price unless it hands around there long enough.
The only way to answer your question is to put in some live trades and see how they are filled. In many of these previous threads, once the trader went live, their strategy didn't work nearly as well in real time and they had to abandon it, so just a heads up.