My background and position on this is best summed up as one of the early implementers of DNSSEC and now working for a gTLD/ccTLD registry. In between I spent a lot of time developing, redeveloping DNSSEC in the face of operational realities. (To those who are critics of DNSSEC, I ask forgiveness for my wasted middle-age.)
DLV is a concept that someone somewhere in the past few years came up with to put needed DNSSEC data in a special location. Although DLV per se is novel in the development of DNSSEC, it is well in-line with the earliest intentions of the protocol dreamers.
The original DNSSEC design was to allow any resolver (client) to decide how it would collect the needed records to substantiate an answer. In the mid to late 90's we tried to figure out how to first express a policy and then come up with something that could take the policy and direct the operation of a DNS validator (the thing that gives a thumbs up or down to an answer after checking the DNSSEC stuff). We punted, resulting in RFC 3008, which said that the only "common" policy was to follow the tree, i.e., root signs tlds, tlds, sign down, etc. A few years later, a project called FMESHD to reopen the policy to be more general. Again, the problem proved too big to solve.
Why DLV is different from these two failures is that we had been trying to solve the general case without a validator in hand. (We did have validators, but nothing that was integrated with a real name server.) DLV is starting from an implementation and is a pragmatic attack on the problem. DLV is not as general as the original idea, but wider than RFC 3008.
The main concern with DLV is that is it not scaleable. That's inherent in the problem so I am not surprised. The tradeoff is that you can go "off the tree" but at the cost of "knowing where you are going off the tree."
Some folks feel that DLV will compete with TLD registries and delay their interest. Or maybe, for the same reason, spur their interest. My opinion is neither, DLV is orthogonal to the TLDs. DLV may be a good measure of interest in DNSSEC though. Either there will be no interest, a quick spike in interest, or a sustained growth. My guess is the middle option - a lot of early registrations and then slow growth. If that's the case, scaling isn't the concern and it won't spur the registries to add DNSSEC.
So, ISC's DLV operation? The developers of BIND are free to distribute code with a validation policy that looks up data in their DLV. If all works, then all is good. If it's a disaster, ISC's DLV will cease and the code will cease to have the feature. "Let the market decide." I don't think that what the pro-s and anti-s *think* matters as much as having tangible data on what *happened*.
If the techies still rule the Internet, something like DLV ought to be given a try. Show off a technical solution and use that as an example of the way forward. We've been stalling long enough trying to move policy makers to sign the root zone.