I don't really know the collector mindset, but I assume they just treat a 8M Pack with Radical Dreamers as though it were a cartridge (In other words, they may judge it based on physical condition and whatnot, although that might be difficult since a "Sealed" 8M Memory Pack is most certainly empty, while one with Radical Dreamers is certainly not sealed.).
Thus, having a "Real" Radical Dreamers 8M Pack is, in their minds, very much like having a "Real" Sealed Chrono Trigger.

Again, though, this is what makes the scenario of the packs being writable again potentially hazardous. It would wreck the value of the Radical Dreamers data, while at the same time have carts be overwritten (Possibly carts which may have unidentified rare data themselves) with "copy" data.