There is a LOT of Undumped Satellaview game data that is unaccounted for. We do not even have all the games that could be "downloaded" like Radical Dreamers, never mind the Soundlink programs (Off the top of my head, the Kirby no Omachahako line is not complete, we're missing the "Bakusho Mondai" version of Wario's Woods, There's probably a LOT of "Tamori no Picross" segments, and other celebrity game lines include "Yuki no Jigsaws" and "WAIWAI Kids". There's also Satellaview variations of commerical releases that aren't dumped. Soundlink data? There's so much Soundlink data not accounted for it'd make this post a really long one.). These could take hundreds upon hundreds more Memory Packs being obtained to be properly archived - and most of the time a pack such as that is identified before a purchase, it ends up in the hands of a hoarding collector rather than a true archiver.
And quite a few of the collectors probably don't even know what they're buying.
To the best of my knowledge there is no "current" Method to re-write data into a Memory Pack - and that is likely for the best, since I'm still in the pursuit of data preservation, and being able to re-write data into the Packs could be a real hazard for that.
I've asked other collectors high and low and they know of nothing that would resemble that, as well. Most likely, one was never developed because interest in the Satellaview is a recent phenomenon (Which I probably blame myself partly for).
Therefore, the most likely scenario is that that Radical Dreamers Memory Pack has been going around for many years. I have heard from some buddies that Squaresoft's Satellaview game library does not "expire" like some other titles, which adds to their collectibility.
Memory Packs can hold up to 8M (1024kb) of data. To the best of my knowledge, data tended to come in chunks ranging from 1M to taking up the whole Memory Pack, and file size was more or less your major concern when dealing with the downloads.
http://bsx.superfamicom.org/