Fair enough. I guess my point should have been: With proper tracking of changes and work done between the environments, finding differing versions could be the lowest hanging fruit.
That was my response to your original question of how they found got to haproxy as the root cause so quickly.
Sure, mirroring hardware and performance can help, if you can afford it (which is rare). However, you'd also probably agree it's pretty rare to find an issue caused cumulative amounts of uptime or load. Mis-matched software versions or configurations are a far more likely culprit in my experience.
Horses not zebras...
