As far as I have found out the max texture dimension limit is 65Kx32K for Cuda v2. A more practical limit is the actual size of the VRAM where it has to fit and share with all other textures. In practical terms most CUDA cards have 2,3, or 4GB on board.
For US2 the VRAM size needed was not the problem (240MB), but the number of rgb texture maps (100) and grayscale maps(86). For a 600 series Cuda card the limits are 144 and 72, For a GTX 580 it is 64 and 32 if I recall correctly.
So if the number would be cut by half or even lower by combining them, that would be great
Thank you for looking into this