There are plenty of much cheaper telescopes in that 6" aperture range. My 152mm was only $1k. My polar mount was $1500. Even adding in a tracking scope/camera to attach is still a fraction of the price of single lens. Tack on a similar SBIG dedicated astro camera and cheap laptop to run the guiding and imaging would still come in under that price tag.
So, is there an advantage of having all of the lenses on the same tracking platform to justify the expense of the single mount? If you place individual 6" scopes in an area where humans could comfortably move between them all pointed at the same object or even slightly different areas to get the wider image, would that not be the same/similar result? Essentially, building the VLA but with commodity off-the-shelf visible scopes.
It's more of a "that they could do it at all" sort of feat. They're coming in somewhat cheaper (probably) and at lower project risk by using off the shelf professional camera lenses than by having tubes made for the purpose.
Your 6" scope is slower, probably much slower, than the telephoto lens they used. There really aren't any amateur telescope tubes I know of that you could directly compare to the 143mm aperture f2.8 Canon lens. The right comparison would be to a 6" apo, which would run $8K-$16K and still be slower.
You of course are correct regarding f-value. My specific scope maths out to an unusual f/4.8 at 731mm focal length. However, I'm not trying to take 1/100th images. I'm doing 30s exposures, so a f/2.8 vs f/4.8 isn't that bad of a trade off.
Even if this isn't doing the same "science", it would be an interesting thing to play with for sciene. Instead of stacking images from the same camera, just stack each image from the array. Or capturing an entire mosaic in one "snap" which is essentially what WASP is doing (mentioned in a post from yesterday).
That's almost certainly an achromat unless you got a screaming deal I want to know about. It's not in the same league optically as the Canon lens, which is more like an apochromat, even though you'd probably be disappointed using the Canon lens as a visual telescope - it will be tough getting and keeping sharp focus on stars with the Canon. They had to use a feedback control system on the focuser in the early paper. They also use a lot of image processing.
Also they're not so much using the speed of the lens for shorter exposure times but for field of view and for high sensitivity.
In general photographic lenses make mediocre telescopes and telescopes make mediocre photographic lenses - try using one of your tubes for some terrestrial photography to see. So it's pretty amazing that the Canon lens performs so well to begin with, that they're able to use it like a fast apochromat, and even more so that they're able to build it out to be roughly equivalent to a really large apochromat. With eight lenses, the early paper claims the instrument is equivalent to a 40cm f/1 refractor. How would you build such a thing? Well, this is how.
So, is there an advantage of having all of the lenses on the same tracking platform to justify the expense of the single mount? If you place individual 6" scopes in an area where humans could comfortably move between them all pointed at the same object or even slightly different areas to get the wider image, would that not be the same/similar result? Essentially, building the VLA but with commodity off-the-shelf visible scopes.