The only real disadvantage of the global needle is its coloring. It doesn't have has good a contrast as the non-global needle. The global needle is red (north) and white, but the red end has a sizable patch of whitish glow-in-the-dark material, which could be confusing under stressful conditions - but not too bad. The non-global needle is red (north) and black, and the red end has a much smaller patch of whitiish glow-in-the-dark material.
As I don't do much world traveling with a compass these days I don't need one. If you might need the compass elsewhere in the world then by all means, get a global needle.
I haven't mentioned the compasses sold under the Silva trademark in the U.S. I don't buy them because they aren't really made by Silva. Instead they are made by someone else (don't know who) and then sold under the Silva trademark by Johnson Outdoors (the same people who market Eureka tents and Old Town canoes.). Johnson Outdoors used to sell compasses for the real Silva in the U.S. and the the filing for the U.S. trademark, but when Silva bought Brunton in 1996 or so Silva wanted to sell their compasses through Brunton instead of Johnson Outdoors, but JO wouldn't give up the trademark. It bugs me that Johnson Outdoors wouldn't allow the real Silva to have their own trademark. That's just me.
Navigation with a GPS has changed things a lot for me. Rather than getting bearings off of a map I tend to use waypoints on a GPS and let the GPS to calculate the bearings, and then I use a compass to sight/follow the bearing. The map is still critical for visualizing landmarks (after orienting the map to north with the compass) and tracking waypoints. I use a UTM grid from
http://www.maptools.com to convert waypoint UTM coordinates to and from the maps. So my primary use of compass is orienting the map and sighting bearings taken from the GPS. As much as possible I try to pre-load the GPS with key waypoints using ExpertGPS on the PC before heading out.
Of course if the GPS stops functioning I can just use the map and compass the "old fashioned" way, but the GPS just makes it much easier and more accurate.
Ken