I can't speak for their triple, but the Allagash White dregs work perfectly. Dregs from 3 bottles (about a month old according to the date stamps) in 500ml of 1.036 wort, almost blew the lid off the flask by the next night. I split a 10 gallon batch of a classic Wit between the Allagash and some WLP400 for comparison. Both yeasts took off like a banshee and did their thing. Definitely liked the flavor profile of the Allagash better, but the 400 was very nice also.
There are rumors floating around that many of the Allagash beers are of the same yeast. Some rumors say they mix multiple strains. Other rumors say they use a bottling yeast in some products. I have no clue where the truth lays and i'm sure they wont tell you, but their white contained a wonderful yeast that would be quite nice in many Belgian style brews.