I've owned and used both silvas and suuntos, the old silva type 3, 7 and 17 and the suunto m3-g with global needle. These were used for coarse surveying for radio work and casual hiking. Two silvas eventually developed bubbles, one from a crack in the capsule, the suunto (so far) has been bubble free. The main advantage of the global needle is that it will work in the southern hemisphere, though a regular one will eventually point north-ish if you tap it.

One possible advantage of the global needle apart from using it in the south is that the capsule is deeper and the needle itself is further down in the liquid. If a bubble does develop, it may have less effect on this design than on a regular capsule where the needle is closer to the top.