Here's the funny thing... I look at my card, and it has a Samsung RAM chip on it, right above the processor. Call me nuts, but maybe ALL cards have a small amount of X-ram?
Soundfont caching works with System memory, not onboard card memory as I can crank up the memory caching clear up to 100% of my system ram, which is a gig.
I think the main reasons why this card is superior to others on the market is because it can do a TON of stuff in hardware, compared to your budget 30-50 dollar sound card or onboard audio with a DAC from Analog Devices. Another main reason is the incredible snr ratio. Line noise is non existant, whereas on cheaper software-based cards you can hear noises, popping.. stuff like that.
I guess you have to pair up the card with a very good set of headphones to hear a real difference.
As for MIDI support, the reason why I'm so stoked is that with my old SB Live! 512, I could play my MS-DOS games, and select the TRUE GM Midi Synth in games, which was a ton and a half better than OPL3 or the famed Adlib emulation. The output with the GM Synth would be put through my headphones, not through the midi port. At least with my old ancient SB16, I was forced to select OPL3/2/Adlib for MIDI Playback which sucked. Anyways, with my Audigy, running MS-DOS Games with true GM Midi playback, they just didnt sound quite the same, like the onboard wavetable was lacking or had a smaller instrument set. With the X-Fi, I can now listen to Midi's just like I could back in the day with my SB Live 512, with an updated E-MU patch set. The upside of all this is that MIDI sounds wonderful, through a hardware processor, not a software processor, without 3rd party software (like the Yamaha XG/Lite software) I always suspected my card was odd, because I pre-ordered my Audigy before they were actually released, so I had one of the very very first revisions of the cards. It probably had some odd bugs that got worked out in later versions and in the A2's.
Another problem I had with my old Audigy 1, when I would reformat my system and start from scratch, Creative's driver installer would refuse to detect the card. I would have to install the drivers manually, which sometimes worked, but ALWAYS messed up the recording side of my card. If I installed drivers manually, playback worked fine, but I couldnt record anything without mad line noise and popping. I never bought an Audigy 2 because people reported this exact same problem with BOTH Audigy 1 and 2 cards. Looks like some people though have had better luck than I.