Were I a deposed despot on the run? I'd go with a G18 with 33 round mags and a Wakizashi like Morpheus in the Matrix trilogy.
More practical though, FN P90 would probably really fit the bill. Seeing as it's actually a "PDW", namely flat shooting, high rate of fire, and just pointy/nasty enough to keep heads down, and the ballistic compromises giving you a rather large magazine capacity.
If you're poorly supported, and they're closing in, you want to lay down enough fire to have at least a chance to get out of Dodge etc.