For the past few years, I've been the chair for one of the international review panels for Country X's research funding bodies. (It's probably all a matter of public record, but no need to name Country X for this.) I agreed to serve (and chair) the committee with one restriction -- I didn't want to fly out for an all day panel, which is apparently their standard approach. Not that Country X isn't a wonderful destination -- were I single and/or without 3 children, I might well enjoy the chance to fly thousands of miles to Country X on their dime and spend a day or two hanging out and seeing the sights with nothing more stressful on the agenda than going through reviews for some research proposals. But that's not the case.
Year 1 I think they were a little concerned, but I think now they're happy I'm willing to do it and are OK with the process. Recently we had this year's meeting, over several hours on Skype, and it all worked just fine. The size is about that of a small-ish NSF panel -- about a half dozen panelists, usually about ten or so proposals to review. That's a very nice size for an electronic meeting -- I recognize it can get harder for multiple reasons as things get bigger. I don't believe the lack of face-to-face presence changes the outcomes significantly -- whatever the sources of noise are, I don't think the noise is necessarily bigger with this approach.
On the plus side, we must have saved the funding agency on the order of $10,000 or more. Air fare, hotel, etc. isn't cheap for an "international panel". I'm sure they can find better uses for the money -- like supporting research!
I keep hoping to hear that at some point the NSF will experiment with an electronic as opposed to face-to-face panel, if only to see how it goes. From Boston I can deal with taking an early flight to DC for a 1-day panel, but I really try to avoid 2-day panels now, and I'm aware what a drag the trip can be for west coast colleagues. I think the NSF could corral more reviewers (like me) if serving on a panel was easier and less time-consuming, by which I really mean doesn't require a flight.