The ability to select many different pairs for the one bot - with the concept that signals are received for one of the pairs and the bot starts and finishes then awaits the next signal for any of the pairs selected.
Like multi-pair Trading/DCA bots?
Yes - why not have this same option like the dca bot? Surely straight forward to implement.
the issue was that someone might start combo bot on 50 pairs at once and that will crash the system.
Maybe a deal start timeout can be introduced to work around this issue. example 1 new deal per 1 minute
Because its such a pain making multi combo bots
The issue is not the creation of the grids, the issue is having a dump in the market when a lot of grids have 0.25% spacing, all those grids will send thousands of orders which will get queued to be sent to exchange (we have a max amount of orders we can send per minute to avoid our IP getting banned). On top of that, exchanges themselves are slow processing orders. This last dump most grids missed orders, and the delay in order processing surpassed 5 minutes. And that’s before allowing multi coin combos 
You are right we need limits on multi pair either number of coins or space %
Well perhaps put a limit on how many bots you can trigger at once. Personally I’d only use it to trigger one bot at a time.
Do you use a rolling one minute time frame to throttle the API calls?