@nical First of all: this is a very interesting thread; it's nice to have somebody else in the field looking at what we do, thanks!
Batching is indeed a niche case for us: mainly helps in benchmarks. The icon atlas is a missing feature of the new renderer: the old GL renderer had one, for instance; needs somebody to write the code. As for opaque/blended regions: there's some work planned; we have the benefit of a clear content/chrome split, so it's not an immediate priority.