Like most things in life, what you value tends to make one thing more important than another when you consider any object.  This is why programs like editors; programming languages; and in this case, file revision management software, gets such visceral responses from so many of us.   And like many programs and subsystems, as deficiencies become more obvious/acute with a program, when and how they are addressed also play into that value.

Thus, I think it comes back to use case for everyone.  What am I protecting with this subsystem and how does it affect me?

Frankly, the high order bit for me, is usually protection from my own silliness (most important), how easy/natural it is to use/fit into my workflow(next in importance); followed by accidental/on-purpose changes happening by my friends/coworkers 'behind my back'(important); how merges are handled when I'm in a group setting; and IF AND ONLY IF I'm using the tool kit to protect IP for a 'product', how easy it is to support 'releases' past/current/in-development at the same time.

The truth is, when I'm leading product development, that last one moves up a few places, although I know that if the 'fit' or ease of using the tool is not nearly #1, some members of the team will not use said tool in the planned and expected manner - so I think I will tend to value 'ease of use' as the most important attribute for me.

Truth is SCCS and from what I know of BitKeeper, has always met my criteria, certainly for simple programs and even for documents like papers and books. As I said, its what I use day to day (thank you Marc and team).  While I learned the direct get/admin/delta/prs commands, calling them via Eric's "sccs(ucb)" front-end 'fixed' the harder to use part of things.  Frankly, I have aliases 'get' to be 'sccs get' and the like.  

I was at Tektronix and like many when Tichey released RCS by itself, Eric's sccs(ucb) command was not available to me, so it seemed simpler and I was attracted to it.  But I quickly went to UCB and was re-introduced to SCCS using Eric's front-end and I found the difference was a nit.   SCCS was what we used, so that became my go-to and has been for a long time. 

SCCS was our systems at Masscomp, Stellar and later DEC (although DEC for OSF/1 switched to another system whose name I forget which came from OSF).   At LCC, we used what the customer used, so we got to see a lot of them ;-) 

That said, when Thinking Machines released CVS-II (on top of RCS) it did seem like the cvs merge management and production tags tended to be the easier/a good thing.   When we used that system for an HP project at LCC, I will say, the Thinking Machine crew had fixed the two issues I had struggles with SCCS**.   I used cvs again for a few other projects including two start-ups later.

 

Since that time, I have been given Mercurial, SVN, and git. I'll ignore the first two as they seem to have fallen from grace. I personally, find git extremely heavyweight and only deal with it because I have too thanks so linux pushing it into so many FOSS projects.  I can and do have to use it, but my experience is that we fight the tool constantly and I wonder if we are ahead or behind.  The git system supposed to be great for merges and so-called 'pull requests' and I can see if what you value is being able to grab something from someone else - i.e. what Linus does daily (merge lots of peoples 'suggestions') and it probably does make it easier for Linus.  But .... I can say in a product setting, I have observed it is messy to keep track of specific versions of things that make up a 'product.  For instance, I would like to be able to query, get me all the sources that make of the 'Intel Parallel Studio, Cluster Edition'  (I don't think it can be done!!

At least at DEC, when we released Ultrix, we put a tag into the DB and keep a DB around for every file we used for the build.  There was a script that could be run, that get do an 'sccs get' against every file and we could rebuild everything (VAX or PMAX) and it even included some of the 'layered products' that the OS team controlled.

So, my observation at Intel, is we have more people wasting backed time on 'maintaining our common pools' here than we ever did at DEC or at any of start-ups.   As a sr person, I must say hmmmmm

Anyway - that's my 2 cents.  

** Although, I'll believe Larry when he says he fixed said SCCS deficiencies in Bitkeeper.  I will say after a quick examination of doc and his emails, it does sound like he picked up some of the good ideas from other systems, but I can not say I have tried it.