I use them as a line backer against infantry break-throughs just 200m behind my 1 line. On the attack the best way to use them is at night or at bad visibilty just keep them 100 m behind your infantry screen and if they spot something just plot a straight order of "move to contact" on the firing defender. These unit then will usually flee. Panzerschrecks will be killed by the advancing infantry. If you need faster recon result - save a tank, and use recon by death.
On the real recon duty I like them, because the have tracks and can travel cross-country. I like to use them together with infantry carriers (which carry lMGs or ATR - something with binos) as a recce group. This works reasonably well on large maps whereas on smaller maps it usally doesnt, because the is not enough place to manouver. Some human players can be distracted by feint attacts of such a group - the A.I. will open up with its big guns as every one knows, but might also use its arty. Sometime I overran arty spotters with a group like that.
After all, as always - the use of MMGs and carriers for recon is depending a lot on the situation (map, time space, daytime, weather). Amored recon is a nice option to have, I used sometimes.
Up for a PBEM someone?