The WP limit for a device should still be 5% of total writable cache, but since the cache is large, and there is no thick support, it should not be an issue.  All volumes should have the same value, unless the device is smaller than the 5%, then the limit will be the size of the device.  We have performed lots of tests on a single device and compared to a single device on 76, or even a 64 way meta on 76, the performance of a single device is MUCH better on V3.
so VMAX3 have no meta volume !! how can i achieve good performance without meta , what about Write Pending Limit  WP , how is it calculated ,  does a big TB single volume going to have same WP% as any small volume 
VMAX3 , No meta Volume , what about WP