I don't have your drive, but the safest burn speed giving the best chance of a good burn on most of my desktop drives for Verbatim MCC004 media is 8x. A few drives might be slightly better at 6x or 12x.
If 8x is fast enough for you then I'd try that first, otherwise burn at 12x.
If you burn at 16x and faster, you will most probably get suboptimal quality near the outer edge when using some of the not-so-good batches of MCC004.
If you burn at 4x, you will most likely burn at a speed that has not been optimized with your burner, and you might get results that are not as good as when burning at 8x or 12x.