Constantin:
Question is though, do you feel lucky? Since I rarely breadboard, I rely on solutions that ought to work 100% of the time. 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 at $1.47 for the chip, its pricy but I can live with it. After doing some reading though, it seems TXB series workk for SPI, TXS series works for I2C. Which is the proper choice for serial? It seems that the TXB series needs the device to source 2mA to drive it, but the TXS does not.