Well, this filter already uses a floss layer as well as the course pre-filter sponge layer, and this does an excellent job of particulate removal. As Ed pointed out, sintered glass media does a better job as a result of it's (theoretically) higher "specific surface area". Specific surface area is simply the ratio of the media's surface area to it's volume. More surface area means more colonization space for bacteria and a higher nitrification capacity. You can test this yourself by doing an ammonia pull down experiment. Fill each of the test filters (same model) with competing media of choice and in each test tank add equal measures of ammonia. Measure the residual ammonia values each day and plot them for each tank. There are some variables to account for such as difference in flow between the two filters once they are filled with competing media, but the plots should more or less reveal the performance of each media type. There were some tests done by
K. R Reddy comparing the nitrification capabilities and hydraulic resistance properties of gravel substrate versus plastic media
Domestic Wastewater Treatment Using Emergent Plants Cultured in Gravel and Plastic Substrates The high specific surface area gravel substrate beat the living daylights out of the lower surface area plastic media in terms of nitrification. The comparison wasn't done against foam though since this was a substrate test not a filter test. Sintered glass takes this to a higher level supposedly. I caveat that because I have no way of confirming whether in fact x liters of sintered glass media has much more surface area than x liters of foam.
One then has to compare cost versus effectiveness, and the benefits of one weighed against the need for extra performance. If the bio-load is low or medium relative to filter capacity, then as Sam suggests, the cost/benefit ratio may not be worth it for sintered glass, and it would be better to go with foam. If you're running a very high light, high bio-load though you'll likely see a difference, so it really depends on the tanks operating regime.
Cheers,