fwiw I've made my position regarding this clear
it has to be said archive.org have some massive balls in doing this, although it's not new, they've been doing it for about 6 months now (but it's only just hit mainstream news sites)
I was wrong when I said they've not got the CHDs tho, they have a 0.149 set for MAME divided into several large downloads, in addition to a number of the MESS CHDs and other MESS software lists, and a large number of the No-Intro sets.
I actually worry more about archive.org, it's a very important internet resource, and I'd hate to see them with legal bills they can't pay. I have to say I find the decision an odd one because typically with the pages they've archived it's the big file downloads that have been missing (as well as any interactive / streamed server-side content etc. obviously)