It's been over 15 years since I carried two keyboards to work, and so far there has never been a situation that made me wish I had the second board. The advantages of the 2 manuals/sounds etc is FAR outweighed by the convienience/price/space saving.

I can't speak for you, but I really doubt that you NEED to have two kbs at your hands. Lighten the load - you'll feel better and want to play more !