Somehow I also got no reply for my mails to Avexir ( except PR department but that's other story ).
There is no difference if you use 1.50 or 1.65V memory. Heat is almost the same , power usage the same ( depends more from used chips, single/double sided etc ).
Nearly all 2400+ memory kits on the market are 1.65V so you have no big choice.
Almost all 2133+ kits are on the same Hynix IC right now so when you get 2133 11-11-11 1.50V kit then it will be probably on the same IC as 2133 9-11-11 1.65V so you can also run it at 1.50V CL11. 2400 10-12-12 are already good timings as most manufacturers move into 2400 11-13-13 /2600 12-13-13.