Should software-rec questions be migrated en-masse to http://softwarerecs.stackexchange.com/? That site was created because software recommendations were seen as too subjective and therefore not a good fit for most other SE sites. I have been surprised to find such questions here.
No, they shouldn't, for a variety of reasons:
Old questions cannot be migrated. We can only migrate questions that are less than 60 days old. So in most cases, we don't even have the option of migrating.
As a general rule, we don't migrate away questions that are on topic where they were asked. Since software requests can be on topic here, there is no reason to migrate them away.
The Software Recommendations site has very specific guidelines for what makes a good, on topic question. The vast majority of the questions posted here as software requests would not fit those guidelines.
Also consider that we have significant overlap with many other sites. For example, I don't think there is a single question here that wouldn't also be on topic on Super User. Many of our questions are about Ubuntu, so they'd also be on topic on Ask Ubuntu. The various perl, python, shell, bash etc. questions we have would all be on topic on Stack Overflow. We also have questions here that would be on topic on Ask Different, or Elementary SE, or Raspberry Pi SE. So the fact that a question might be on topic elsewhere is not a sufficient reason for migration.
So if you see a new questions which you believe would be better suited to another site (any other site), you can always leave a comment letting the OP know about that site's existence. Take care not to suggest that they cross-post, though. If they want to ask there, they should delete the question here.
No, software-rec questions should not be migrated from Unix & Linux to Software Recommendations. The Software Recommendations site was created because some Stack Exchange sites ban software recommendation questions. Since Unix & Linux allows such questions, they are on-topic here and should not be closed.
Software Recommendations does not accept more subjective questions than the rest of the network. If a question is too subjective for Stack Overflow or Super User or Unix & Linux, it's too subjective for Software Recommendations as well.
The reason for the existence of SR.SE is not that software recommendation questions are harder to answer on other site, but because many Stack Exchange sites are bad at moderating software recommendation questions, and just close them regardless of whether they're answerable or not. Unix & Linux does not have this problem.
A major downside of relegating software recommendation questions to a specialized site is that this site is not good at answering them. Answers on Software Recommendations are generally good (partly because bad answers are moderated more heavily than on other sites), but almost half the questions are unanswered, the worst track record of all Stack Exchange. Software Recommendations is good at moderation but has an expertise problem. It's better to have questions under the eyes of experts, and when it comes to Unix software, the experts are here.
On Software Recommendations, on Unix & Linux and elsewhere, questions asking for software recommendations should follow the Software Recommendations guidelines.
Source: I largely wrote the SR guidelines based on my experience on U&L and other Stack Exchange sites and on the advice of many others, and I moderated SR.SE for a while.
I have not looked closely on the 318 questions that are currently tagged with software-rec on this site (but I do notice that more than 200 of them have been upvoted here).
I think that new software recommendations should only be migrated to Software Recommendations if they
- are on topic there (we don't want to migrate poor question), and
- are not on topic here.
Those are the most basic rules for any migration. Topics between sites often overlap, and if a question could have been posted on any of the two sites, we don't migrate.
Questions about "Applications packaged in *nix distributions" are explicitly on-topic here and therefore I feel that questions that can be answered objectively with a pointer to such software should remain on the U&L site, if the question itself is on-topic or has good answers that makes the overall Q/A topical.
It is highly unlikely that we bulk migrate old questions (we can't) or that we semi-automatically migrate new software recommendation questions in the future.