IMHO a Pred B is a bit wizzy and quick to be providing static ISTAR coverage of a Single Op in a set location in a built up area isn't it? Hence the need for a helo type asset.
I suppose that that helo type asset cold be FireScout UAV or suchlike, but what happens when it all goes to ratsh!t on the ground and troops need immediate evac? A manned asset could potentially drop in and pull out any troops needing immediate medivac.
And what's wrong with Merlin? Nothing per se, but I would hate to use it for conducting overwatch using an IR turret over Basrah when it can be put to better use ferrying troops, equipment etc.