"The SD2 has one of the best General MIDI banks of the modules I've heard"

I would pick Halion any day (or night) over SD2.
I had SD2 for a few weeks, I guess it is ok if you are
Gigging-and-do-not-want-to-drag-laptop-around sort of thing.

SD2 has horrible software to adjust sounds (through MIDI ports!), no USB, needs AC to operate... I can go on. But to give it some credit, it has "ok" sounds for basic use. The biggest problem I see that it is very "outgoing" technology. Once it goes bye-bye, there is no good reason to replace it with same unit.

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Bobby, regardless of your setup, Sonic 3 SE (light version) is free. And I am pretty sure SE has GM sound bank. Free is a good price to pay. If you feel like trying it, here is Steinberg page:
https://www.steinberg.net/en/support/downloads/downloads_halion_sonic_se_3.html

My guess, most of the sound "modules" will go software very soon. So this is a good opportunity to take it for a test drive.