MODFETs: Typo or solid state audio revolution?

[cabritoloco]

Whilst perusing through Ampeg's product page, I ran across a page for an amp with MODFET outs.

MODFET?  Somebody must've made a typo.

But a quick Google search showed that Harvard even the IEEE has written up papers about these devices.

According to wikipedia's MODFET article, MODFETs can be manufactured by epitaxial growth of strained SiGe layer, with the germanium content linearly increasing to about 40-50%. The high content of germanium allows formation of a quantum well structure with high conduction band offset and high density and mobility of charge carriers, resulting in parts with ultra-high speed and low noise.

Now my chemistry/quantum physics knowledge is only pedestrian, so anyone is welcome to correct me, but doesn't a high charge carrier density and mobility decrease gate-source and gate-drain capacitance, which is a major design detriment for MOSFET amplifier designers?

And if it's able to perform well at high frequencies, I would guess that the Rds-on would be lower than conventional MOSFETs.

The benefits of a low noise device go without saying.

Now, I don't have the time to delve into this, and in my brief searching, I found nothing that explored the linear operation of these devices.  They may very well be better used in switch-mode amplifiers.

Can anyone give me the skinny on these devices?  Mouser and Digikey don't have any MODFETs available for order, so I imagine that this technology is still in its infancy.

edit: forgot to include the ampeg amp product page

[teemuk]

Looks like theres not much information about them in the internet... I have to admit that this is the first time I hear about such devices. Google brought up this article:

http://nsr.mij.mrs.org/1/4/complete.mac.html

It seems to focus on fabrication methods and math is not my strenght. There are some charts at the bottom of the page and it looks like the Current-Voltage Characteristics (Fig. 2a) are very similar to MOSFETS.