Are AO-GCMs sensitive enough to take large lakes into account?
The resolution of AO-GCM are not high enough to include lake model in their code, at least as far as I can remember (looking at google scholar, I have not found anything related to lake model in AOGCM).

However, lake model are implemented (and operational) in regional climate model (RCM), such as CRCM5 (Canadian Regional Climate Model v5). See for example Martynov et al. (2012), where they describe the results of implementing lake model in a 45km resolution simulations. On that note, I think that until AOGCM (and now the Earth System Models, which implement carbone cycle) goes to resolution close to 50km, they won't adopt massively such lake models.

From Martynov et al. (2012)

"The  presence  of  lakes  influences  mostly  the  lake-rich region of the Canadian Shield by altering the low-level  air  temperature,  humidity  and  precipitation.  The influence of lakes on the precipitation is most significant over   the   Laurentian   Great   Lakes   and   within   the distance  of  200-300  km  downstream  of  these  lakes,
especially  with  open  water  on  lakes  in  wintertime.  The patterns of enhanced precipitation correspond to regions of the well-known lake effect snow on downwind coasts of  the  Great  Lakes."

Since the effect is rather regional, I suspect that other climate processes are more important for the AOGCM modellers.

Citations

Martynov, Andrey, Laxmi Sushama, René Laprise, Katja Winger, and Bernard Dugas. 2012. “Interactive Lakes in the Canadian Regional Climate Model, Version 5: The Role of Lakes in the Regional Climate of North America.” Tellus A; Vol 64 (2012), February. http://www.tellusa.net/index.php/tellusa/article/view/16226.

On ResearchGate: https://www.researchgate.net/publication/234872039_Interactive_Lakes_in_the_Canadian_Regional_Climate_Model_version_5_The_Role_of_Lakes_in_the_Regional_Climate_of_North_America