[rbclay]

I am doing an extended secondary on an English Barleywine. I can do it at 66F, same temp as primary OR 50F in the basement closet. Being that this will be a 2-3 month secondary there is much less chance of an airlock accidently getting yanked by a kid if I do it in the basement.

I am aging half of the 5G batch on bourbon soaked oak cubes. The other half just aging. Primary is done (5 weeks- pitched on a large yeast cake). OG was 1.103. Current SG 1.032. That attenuation is about the same for this yeast as I got for the other 2 beers I made with it (~65%. NeoBrittania). So it may drop a point or two in secondary, but I am not concerned if it doesn't. I purged both carboys with CO2. I plan to use some yeast at bottling to carbonate.
 
Is there any drawback to doing it at the colder temp?

[euge]

No drawback. Colder would be even better IMO.

[bluesman]

I would age it at cellar temps...50ish is good.

[Hokerer]

Can't think of any reason colder would be a problem.  Probably be beneficial

[tschmidlin]

Replace the airlock with a breathable bung and age it at the lower temp.  

[rbclay]

Like this? I use these for flasks when making starters. Never thought about using it in a carboy.

http://www.northernbrewer.com/brewing/brewing-equipment/fermenting-equipment/yeast-handling/foam-stopper-46-60mm.html