This isn't a solution for 8MB A600/A1200 users, it's a slow option for accelerated Amigas at best. If there was a more effective way of connecting the RR-Net and suitable drivers it might be usable, but really we just need a real, dedicated ethernet or wireless card for the Amiga clockport. Maybe it could have an extra clockport on the card to daisy chain it to another expansion without requiring a splitter.
The A1200 clockport is an 8 bit databus, 4 bit address bus connector with extreme and artificial wait states to allow slow clock chips to work. 4 bit address bus means that there are a total of 16 possible addresses, each one byte wide. Each address is four bytes away from eachother, so there's no way to combine word or long word accesses to get faster access.
There was exactly one (!) card that allowed daisy chaining with exactly one other card and AFAIR it was the Melody+Twister combination. It was specifically designed to allow this kind of thing, and obviously, because each card only used part of the address space.
It is nearly magic that a USB card like the Subway actually works on that kind of bus. The Subway performs much faster on Zorro card clockports due to the better timing though.
The RRNet could work on the Amiga clockport, but it lacks an IRQ which probably makes it awkward software wise (polling for interrupt bits is a bit too retro). Anyway, the speed of such a device (or a redesigned version with IRQ support) on an original A1200 clockport probably won't be much higher than a Subway + USB Ethernet adapter solution, because in the end, it comes down to copying memory across the bottleneck of the clockport.
