Hard to say for you, as everyone uses their vehicle a bit differently and depends on it in different ways, but if it were me, I wouldn't spring for a new tranny until (a) I became convinced the one I had was unrepairable or (b) the one I had completely failed. Now, I'm not saying it's going to get any better, but not immediately resorting to replace what you currently have might give you some additional time to sort out what could be a fixable problem. The fact that a flush changed the symptoms - even temporarily - leads me to believe the possibility of a fix might be there.
On the other hand, if you're on the road with it all the time and can't afford to have it let you down, it may be the peace of mind of having a new transmission will be worth the expenditure for you........again, the possibility of having to replace it is out there, so only you can decide if it's worth trying to sort out what you have or doing away with the problem altogether by making the swap.
Just my thoughts....