I have had great success with level-shifting via the TXB series on the SPI bus. So, I'll keep adding the three chips necessary (one IC, two decoupling caps) and call it a day.
And that is not necessarily a bad or even a 'overkill' attitude to take. I just jumped in to try and squelch the thought that some how a resistor(s) is a slower device then an FET transistor(s), when in fact the opposite is closer to the truth. Every transistors comes with a specified 'speed' limitations, it's stated in their datasheets. This limit may or may not effect anything depending on the application it is used in. Resistors don't have any 'speed' limitation unless excessive lead length, circuit layout, or wire wound resistors are included in a circuit analysis, which equally would apply to transistors also.
Lefty