Does it give different results if you buy anything or not ?
I suspect something like : the buying action count as a "punching something" action ?
Even if that's not really convincing...
i think you got something
So when you buy something when your combo bar is full you will lose flybash at the end of it if you don't bash another roman after buying something and while still being on combo
To be sure that you will still have flybash at the end of the combo, the combo bar should drop a big amount when you bash the roman after the merchant
If you buy something when you have flybash but without the combo bar you will not lose it
OOOOOH, then I assume we shall wait until the bar is depleted ( 4-5 seconds ) before purchasing then
Now the trick becomes not worth / useless
Thanks Nekin

Full timing of both sequences could help I guess...
I might record that later and see
Sorry, I don't want to risk giving a proof of this trick to be worth it ...
I need to put all the chances on my side if I want to reclaim a good time
I'll get some grinding next week