Nice post. Before I write anything critical about it, I want to make clear that I think the Kanban approach is very interesting.
I have a few thoughts though, as I always do when considering agile versus "heavy" processes for software development.
First, there seems to be a bit of confusion regarding "heavy processes" and "waterfall models". Heavy processes do not necessarily imply a waterfall approach to development. I was working 20 years ago on heavy (really heavy mil-spec projects) which were employing iterative, incremental development models with frequent releases and continuous integration, nightly builds and test-driven-development, before so-called agile approaches became popular.
My second thought is around development speed and quality. The post makes a significant claim regarding the performance improvement achievable without sacrificing quality. I would love to see real stats on this across a broad spectrum of projects. It also depends upon how you define "quality", and what level of quality is acceptable. Most applications developed today for the public (especially mobile apps and web content) have very low quality requirements, as the implications of a "glitch" are not that severe. On the other hand, banking and online payment software have significantly higher quality needs. Moving on to military, medical device, and other software upon which lives depend, definable, demonstrable quality objectives are required.
Over the years (over 25 years now – man I feel old suddenly) I have led or been involved with software projects following a large number of different processes, from no identifiable process at all, to heavy mil-spec processes, to modern agile processes.
Each approach had its own value, even the "no process" model, and each had its weaknesses. The challenge I have with many proponents of agile processes is that they promote agile as inherently superior to heavy processes (of course, heavy-process oriented folks do much the same towards agile folks).
In my experience, no model works for all situations. Much like selecting a technology or a programming language, it is important to select the right approach for the right job, without being too enamoured with any one approach. While a mil-spec approach is not appropriate for a small team in a start-up, an agile methodology is equally inappropriate for a 10 year, multi-billion dollar, life-critical military project employing hundreds to thousands of developers.
Recently (well, in the last 10 years), I have become a big fan of what I term "just enough process" (which I talked about in a previous post). Always use the right tools and processes for the right job.