Mystery cuckoo in Las Macanas

Guido Berguido sent in a report of his group's visit to Ciénaga de Las Macanas.

While leading an Advantage Tours birding group on our way back from Coiba Island last Saturday June 20th, I decided to break the drive and do a brief visit at Las Macanas wetlands. Upon our arrival we were greeted by a covey of Crested Bobwhites at the parking lot, promptly followed by views of Mouse-colored Tyrannulets, and flocks of Black-bellied Whistling-ducks, as well as a vocal Rufous-browed Peppershrike. Later we saw a pair of Pale-eyed Pygmy Tyrants near some Common Tody-flycatchers, and a flock of "Veraguan" Brown-throated Parakeets. While walking around the water's edge, we saw lots of Grooved-billed Anis and were fortunate to spot a roosting Striped Owl.

Towards mid-morning we decided to wrap it up. Back at the parking lot we heard a pair of Gray-necked Woodrails nearby and decided to wait under the shade to try to see them. Suddenly, a cuckoo flew in front of us and perched on a tree about 15ft. high some 30 ft. away from us. At first I thought it was just a Yellow-billed Cuckoo, but when it flew to another nearby tree I didn't notice any rufous in the primaries, and it seemed to have a much duller gray-brown. I thought it may just be a stranded young Yellow-billed... However, having heard about the possibility of the similar-looking Pearly-breasted Cuckoo in Panama, I decided to try to document the sighting. I managed to shoot a couple of pictures with a small point-and-shoot Canon Camera. What do you think ?
On the way out to the highway we stopped at some fields and found a bunch of egrets as well as 7 Glossy Ibises, Yellow-headed Vultures and a pair of Aplomado Falcons.

The cuckoo is, of course, the most interesting bit. Yellow-billed Cuckoo has never been formally recorded in Panama during the boreal summer (no records from mid-May to mid-August), although (as pointed out by Guido) there are "immature [specimens] collected in South America in [the boreal] summer." The other possibility is, of course, Pearly-breasted Cuckoo, which again has never been formally recorded in Panama. We are only aware of its existence because of a recent reevaluation of an odd cuckoo photograph from 2007. Apart from a minimal difference (and the fact that Pearly-breasted is a really rare vagrant to northern South America), the best field mark is the lack of rufous on the primaries typical of Yellow-billed Cuckoo. This is very evident in flight, but can be seen even on perched birds. According to Guido, they did not see any rufous on their cuckoo's wings:

Cuando lo estabamos viendo, yo estaba bien conciente de buscar el rufo para autenticar que en realidad era un Yellow'billed Cuckoo pero en realidad no lo vi.. incluso en el momento le dije a la gente que buscaran para ver si le veian el rufo... y entre el par que me contestó, nadie logró verle el rufo... He recibido respuesta de tres de los participantes de la excursion y ellos recuerdan que yo les pregunté si veian rufo en las alas del cuclillo y todos me confirmaron que en efecto nuestra ave NO TENIA nada de rufo en las alas !!

What do you think? Do you see any rufous on the wings? Do you have any insights that the Panama Records Committee should consider when considering this record?