I haven't read Barlow's edition myself Merlin, but it has been discussed on other fora I frequent extensively and the general opinion there has been that Barlow does an excellent job of demolishing the "Old School" view of Davis and Brown.

One interesting argument, which I gather from second hand reports is presented by Barlow, is that since Guy of Amiens (the probable author of the Carmen) was French and William of Poitiers was Norman, Poitier's Gesta reads almost like a Norman 'answer' or 'response' to Amiens' French view of the battle.

So Amiens has William the Conqueror leaving the English dead as carrion on the battlefield, while Poitiers despicts him allowing the locals to bury them. Similarly, Poitiers doesn't go into details on how Harold died, while Amiens goes into great detail, emphasising that he was killed by French as opposed to Norman knights. On the other hand, Poitiers depicts the English rearguard action at the Malfosse as a French failure where the Normans saved the day, while Amiens leaves this incident out of the Carmen completely.

If the Carmen is an authentic early account of the battle, it includes some interesting details. Including (depending on your translation) evidence of the Norman use of crossbows at Hastings.

Let me know if you have any trouble getting a copy. I have some friends who may be able to help you out.

Cheers,
Thiu

Visit CLADES VARIANA
Help create the film of Varus' lost legions ...