+1
On v6.1 you could change the md_write_limit manually on disk.cfg, and I did several tests at the time and never noticed any difference in write speed, maybe the setting was needless and that's way it was removed, AFAIK Tom never explained it, nor how stripes vs window works.
I find that I get best results with md_num_stripes set to aprx. twice the md_sync_window value.
nr_requests is not an unRAID tunable, it's a Linux setting, it was a workaround found to fix the SAS2LP issue before the md_sync_thresh tunable was added, it's possible that changing it affects write performance, though I believe nobody ever noticed any issue, it can still be useful, e.g., if a server as both a SAS2LP and a LSI controller setting nr_request to 8 and md_sync_thresh close to md_sync_window gives the best performance.