Reporting back: I subsequently found some numbers at http://newtonsales.com/emate.htm
which relate to my query.
Further to this, and on a more subjective level, I noticed when doing a web trawl re. the eMate a few weeks ago that some of the reviews spoke of the machine being unable even to keep up with fast typing. I later acquired two emates, and have been able to test one with the upgrade card and one without. Both have been restored to factory settings in terms of installed software, and it's true: the stock eMate indeed struggles to keep up with even moderately fast typing. However, by comparison, the one with the upgrade does very nicely. I cite this as an illustration of what the numbers in the link cited might actually mean.
I have used a MP2000/2100 since 1998, so am familiar with the platform, which I still think a fabulous technology, and I have to say that the upgraded eMate for most uses is far from being crippled. It's still a bit slow, but not at all unusable. I would, however, tend to agree that the stock eMate is best at looking 'purdy', and that it really was a crippled machine that ought not to have made it to market in the configuration that it had. It's the old, old Apple story: they wanted you to buy the add-ons, when at least the most important of the 'add-ons', decent memory, should have been included from the outset.