I'd be interested in reading a source to this claim because I did quite a bit of research on memcached vs redis a couple of years ago and the conclusion I came to was that redis's performance was at least comparable to memcached, but potentially even faster in the (then new) latest engine.

I've also found redis to be easier to manage than memcached and easier to scale too - which was one of the clinching points that sold that K/V DB to us.

Pragmatically, the performance of redis vs memcached is similar enough for most people that very few people would need to decide based solely on throughput and read time alone. For example our application would regularly see hundreds of thousands of concurrent users with several million keys stored and yet our redis server was barely taxed at all.

It has been a while but is that with Redis configured not to store things on disk and configured properly for the machine?

(Again) It has been a while but I remember from my own tests Redis being faster. Granted I could've been exploiting some of redis's data types that allowed for my contradictory results (which is what you're saying).

I'm in no way saying memcache isn't awesome. It is great, dead simple, and works like a charm OOB. I used it in production for years with no real issues (except multi key performance).

Source?

not only faster but much more stable