LaserSoft Imaging

I recently bought SF 5.5 under Mac OS 10.2.1 which works fine with my Epson 2450 and USB. I tried now the SF 6 demo and realize that it gives firewire support with the same scanner and system.
So, my question is: Why do you support Firewire under SF 6 but not under SF 5.5. Is it purely marketing?
With SF 5.5 I have anything I need, I don't need the extra features of SF 6.
So when do you build in the Firewire support into SF 5.5, or do you want to obligate people to upgrade?

At the state when the first SilverFast OSX versions were ready the general software version state was 5.5. At this time SilverFast did not install device drivers/libraries for USB or FireWire devices, and the manufacturer original software had to be installed, too.

Well at that state there was only a Epson USB software which supported OSX.

I think it's just fair that you update your software, not only the latest version of it.
The same software offers firewire support in Mac OS 9, and it should support it under the rest of operation sytems too.
Paying USD 77 for a upgrade with firewire support under OS X , is a bit too much. Who's knows anyway if I buy SF 6 it will not support Photoshop 8 in the future or any other new development, following your philosophy.
I understand, that you don't do all this for fun, like me you run a business and earn money with it, but just play fair!