Hi,
As I have an A4000 running the Video Toaster 4000 flyer I can tell you that the Toastscan will be your best option. It will also alow you to use a standard PC monitor so you can toss that annoying 1084 or 1960 away. Toastscans are hard to find and Software Hut is about the only place to get one. They just got word of about 200 more being made and shipped from Germany where they are made. Hurry they wont last long.
The reason to go with the Toastscan is that most adapters made for the Amiga do not alow you to use the Video Toaster and the PC monitor as it must be genlocked and only the standard Amiga monitors will alow this. The Toastscans alow the genlocked video modes to be used as well as most other amiga modes on a PC monitor.
Also like you said there is only one video slot in the Amiga so you must put the VT card in there so no other graphics card can be used.
