The various betas are floating around on P2P networks, although they are in other collections like TOSEC (IOW, there is no 'Kickstarts - Beta' collection). 1.4a15 and 1.4b1 are in the TOSEC Kickstart and Workbench collections, and there are some miscellaneous 2.0 builds buried within the TOSEC Amiga Applications collection. I am currently in the middle of compiling some Amiga screenshots for a friend's site, so in the process I will make a list of all the current Kickstart and Workbench prototypes I have (I will say this - there are more proto Kickstart images than there are Workbenches to go with them - so I just test many of the 2.0 Kickstarts with the earliest 2.0 I could find, which was the A3000-bundled version), and whether the ROM is a standard Kickstart at $F00000 (512K)/$F80000 (256K), or a 'special' one meant for softkicking with either Kickit or Rekick. It would be nice if WinUAE natively supported Kickit/Rekick images, but for now i just boot with 1.3, CTRL-D out of the startup-sequence, and run Kickit to load the softkick image.
There is no extras disk that I know of for 1.4a15, all I have is Workbench. 1.4b1 does come with four disks, one of which has Kickit and the $200000 Kickstart image, one is the Workbench, one is Extras, and one is Autodocs+Includes.
Edit: Also, for the record - when booting 1.4b1 (as listed in the filename), the boot image says "1.4 Alpha 18".
