This is pretty much my job. I develop climate analysis software at a DOE national lab. We have a pretty reasonable career ladder for the "research software engineer". A quick sample: Me: Recent graduate (2012), early career. All dev, all the time. Lead Dev: ~15-20 years experience, minor project management tasks, mostly just dev work. Gets author credit on scientists' papers every once in a while for his help in gene…
There are no promotions between entry-level and lead dev? I don't know that I'd call it a reasonable career ladder if the second rung is 15 years away.
The consensus is that this promotes a more egalitarian culture, and prevents people from being locked in to roles they don't prefer. Senior staff are free to spend a few years managing a large project or in a leadership role, then back off to get back into the research.