While it may look like the card is more 'complete' with the MPC-010Add-On, that is not entirely true.. For what it's worth, I have tried the card's CMI MIDI without the MPC010 add on and the MPU401 works flawlessly. If you are using it on a 386 or later, with SoftMPU it drives my MT32-Pi and Sound Canvas devices perfectly fine.
The real appeal of the addon card as far as I am concerned is that:
a) It's a great great great ISA card and an intelligent mode MPU in one ISA slot, which may be a super big deal if you are using a platform with very few ISA expansion slots (It happens..)
b) The release version will allow you to enable PCMIDI alongside CMI MIDI on different ports and IRQs.. So in theory you could run a GM wavetable daughterboard or a Sound Canvas device on CMIMIDI while the PCMIDI drives a WP32 McCake or an external MT-32 device. This is a very desirable setup, but not necessarily something everyone would need, not to mention can be achieved with a discrete PCMIDI card regardless.
So yeah, don't be afraid to pull the trigger on this without the addon. It is absolutely unmatched for quality in its price bracket. Leo and co did a fantastic job on this. Now I need to go back to playing some games 🤣
I will record some more FM game music tomorrow, I am thinking Sim City 2000, Daggerfall, Ultima Underworld and UFO: Enemy Unknown. Cheers.