NGINX will only give you an advantage if you are serving mostly static data.
UnixGuru sold shared hosting based on NGINX > Varnish > Apache from March 2010 to May 2015 and if set up correctly NGINX is configured to server everything except PHP, which is passed to Varnish, if not cached is then passed to Apache, which should honour .htaccess.
UnixGuru stills sells this on managed VPSs and custom dedicated servers for customers who have outgrown shared hosting.
We now use LiteSpeed for the Shared/Reseller platform, as it simplifies things and is actually faster than the NGINX/Varnish/Apache setup for the random workload that shared hosting has. (LSCache replaced Varnish).
In the 5 years we sold NGINX, the main benefit we saw, was less Apache processes needed and therefore approximately a 75% saving on memory allocated to the webserver stack.
You can use that extra memory to cram 4 times as many customers onto the server, or to cache more files, reducing disk I/O (the enemy of shared hosting). We used it for the latter.
The main speed gain here, came from Varnish (which you haven't mentioned), which allowed servers to withstand a deluge of visits, including one site which got 750,000 visitors one day as it was mentioned on Slashdot & Reddit.
Varnish would serve around 40% of the "Apache" content during the busiest times.
We had developed our own NGINX/Varnish system for DirectAdmin.
However, for some customers who wanted CPanel on their VPS servers we had installed UNIXY's NGINX, Varnish plugin, which was well maintained and easy to use, and appeared totally transparent to the customer, everything worked, just faster.
So we would heartily recommend the UNIXY plugin.
Please note we have NO stake in UNIXY the name of the companies are just because we both use Unix.