I don't know how DAZ works to be honest but if the new cards from Nvidia with the NV link allow them to access all of the VRAM contained on both cards, my guess would be that most of the rendering programs would patch their programs to utilized this feature. My suggestion is more about future proofing than anything. Like your render rig you are building for example, you want to put in a 1080ti, the 2080ti is really expensive, a 2080 is not that much more than a 1080ti here in the states. The 2080 has GDDR6 in it and may outperform the 1080ti in the area of rendering even with less VRAM. My thought was, if the NV link does allow two cards to use all of the memory contained on them and the program supports this you may be miles ahead in performance from the 10 series cards. If you can have two 2080s working together with 16 GB of ram available to them that could cut render times down significantly. Maybe get one now, and a second in six months or a year.
Just something to think about.