Yes, currently I end up with merge throttling when indexing at the low and high ends of our indexing rates. The high ends do not surprise me so much as the low ends. It doesn't make sense to me that I'm not able to keep up with merging if throttling is disabled and I'm doing low EPS.
My struggle with that is chronicled here... Merge throttling is preventing heavy bulk indexing (ES 1.7.5).