I presume it's an improvement because the processor won't run at 2.7V at 16 MHz. In fact you can't run above 10 MHz at that voltage.
On one of my homebrew pcbs, I can select Vcc=5V or 3.3V, and both Duemilanove and UNO chips run
fine at either voltage using a 16-Mhz xtal. I know the d/s curves indicate you can only run up to about
13.3-Mhz at 3.3V, but it seems to work fine at 16-Mhz [even though most people were recommending
against it on other recent threads - I'll just use it till it stops working, :-)].
Also, I just bought a couple of JeeNode modules this past week, and they interestingly include a 16-Mhz
resonator and the v.reg is a 3.3V part. And they've been selling commerically for a few years, so .... ???