I just got my asymmetrical sail (A-sail) and I love it. It too is in a ATN sleeve. However to answer your question about a whisker pole, the answer is yes I use both. The variables are many and depends on which type of boat you have and mast set-up.
My boat has a B&R rig and doesn't go dead downwind (DDW) very well. The jib is small and almost worthless. The only way for me to go dead downwind is wing to wing. It is not a good sail plan. If I pole out the jib my options are many and the boat move well. Wind speed plays a big factor here. In light winds, less than 10 knots I have to pole out the jib to sail. In moderate winds (10-15) I have to be careful on helm control to keep the sails from gybing and using the whisker pole helps here a lot. In heavy winds I just use the mainsail.
The asymmetrical sail I haven't poled out yet DDW but was told I could with some limitations on wind angle from the stern. Since I singlehand the boat, I am not going to go there with that set-up. Maybe others with more experience here can. However with the asymmetrical sail in my arsenal, sailing is now a pleasure with the wind aft of the beam. With the ATN sleeve I can sail my boat alone. I set-up my all my lines aft to the cockpit.
Masthead rigs sail much better DDW and the argument for a pole out jib/Genny can be made in light winds. I don't think I would pole out a Genny bigger than 130% especially in winds greater than 13 knots with a crew of two. The only time I pole out my jib is on a long run greater than 45 minutes for the effort it takes to set it up. Maybe if I had someone else on-board that might change the time somewhat.
The bottom line is really your boat and your sailing area. If the winds are predominately out of a direction that would require you going DDW and winds are light most of the time, I would definitely consider a whisker pole. The other consideration is the time it takes to set up the pole and if you need to gybe a lot with a short hand crew. Most people think it is too much effort for all that work. Take out precious time from pure enjoyment of sailing and beer drinking (or your favorite adult beverage).