I may have my wife try them out I actually don't really have time to concentrate on a demo account right now I manage (2) of my accounts options and futures and my kids long term account which actually takes alot of my time. Sometimes missing entries in my futures account. Yes that is the fact most people will fail at these combines but as you have said so far at their current business model you have a decent chance of being paid at OneUp for now. Can I ask what commissions and fees they are charging you?
I'm more of a positional swing trader at heart, so my trades are planned in advance, and I usually use limit orders to execute strategies, ideally around MM stop run areas. Sometimes it takes many many hours to get a fill, sometimes I completely miss out. I say this because I also trade separate personal accounts but that it's easier for me to manage an additional oneup one due to the aforementioned -- kind of like having multiple browser tabs open simultaneously and you only adjust occasionally.
To answer your question, the main fees you should be concerned with are monthly account fees + commission. Mes Capital covers the account fee whereas TopStep separately charges you $85 per month for every market you trade in. For me with CL it's $4.72 commission per round trip per contract and you can look up their commission schedule for other instruments on their website under 'funded trader commissions'. That's about the same price as I pay with TD Ameritrade so it's pretty fair in my opinion.
