1. Even if the NV35 is not on time, it'll still be slightly before the R400
2. The 256-bit memory interface is one the most reliable piece of information we got on the NV35, another one which we can also be sure of is it's with Low K. The NV35 *will* be on a 256-bit memory interface: it's a fact
BTW, the less certain piece of information I said about the NV35 is the 625Mhz core. It could be easily less ( even significantly less, who knows... ) , but not more.