To add another ingredient to the mix,I would like to add that I use my LT with MidiNotate where I store all of my midi's I use for vocals. Since I have to read some of the music and have not memorized all of the lyrics,I simply call up the tune from my LT and "VOILA", there is the sheet music arranged as a lead sheet with the lyrics. With the pages flipping as the music plays.
I have a choice of playing the file through the LT and into my Technics KN7000,or muting the line in and synching my MidiNotate to the same midi track saved on the SD of my KB. As mentioned,this always gives me better sound quality. I admit this takes a little pre-planning,but in my situation I can plan ahead what I will be playing.
I tried using the Yamaha XG Softsynth but it wants to conflict with my MidiNotate. As far as simply playing along with Midi's, the SD cards provide great storage as well as the ability to make any playlists I want and play them as a medley or single.

If anyone has any ideas about a superior softsynth that doesn't have to be exclusive, I would like to know about it.
Thanks
Bernie