The "armhf tax" is that you tend to have to build your own images for stuff :( Then you need your own build infra (or "heath robinson" qemu builds) because pis run out of memory building a lot of stuff... but mainly if C++ is involved so ymmv.
That said, I got a rack of 8 pis doing nothing right now, so...
(unrelated http://www.bitscope.com/product/BB04/ is handy if you want to rack a lotta pis, not affliated...)
There is probably a micro business for someone running a slick docker build system for armhf handling the qemu emulation or toolchain dirtiness "under the hood" in the cloud somewhere, on x86-64 boxes with a lot more than 1GB of RAM.