I doubt one could squeeze in a smoke unit, much less 2. I have no regrets about buying one.
Bear in mind that this is a completely new design, with smaller drive trains and a new miniature PS3 board. It is not just a reuse of old machinery and electronics. As with anything totally new, bugs may pop up; as of now I haven't seen any other than my trackwork issue on a sensitive switch (a dip in mainline and a curve that goes down a grade).