It seems that the answer is mostly .... yes.

However..... it's always a good idea to have the sub on a switch you can easily turn on and off..... because you really have to know the room and the default EQ on the system, and you really should A/B sub on/sub off.

Many folks in home studios tend to buy a sub, and start mixing without really doing anything to see where their room is at. The room affects what you hear more than most folks realize. If your room is canceling the lows at your chair, you will tend to mix bass heavy music, just as mixing with tiny speakers such as 3" or even 5" cones. Adding a sub to make up for the lack of lows with out really EQ'ing the room is a recipe for trouble.

Learn the system you work with and you can produce good sounding mixes regardless of the size of the speakers, using headphones, or having, or not having a sub kicking those lows.

But I will say this.... mixing with a well balanced system with a sub in it is nothing but sweet ear candy.

Personally, I have 5" 50w cones and a 10" 100w sub and I really enjoy the mixing.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.