There are pros and cons to doing a 2 yr gpr/aegd. It really depends on what you want to get out of it. From my experience, the second year has the potential to allow you to do more procedures at a relatively advanced level (i.e implants, perio surgey, sedation cases, and molar endo), another plus is the ability to follow up your patients for longer duration (you can eval your work and see your successes and failures!).In a GPR you have to do a set number of off-service rotations which takes away from your clinical time (medicine,ER, Anesthesia), usually they are done in the first year, which means the second year is dedicated to patient care (I had to do 2 weeks of endoscopy rotation sedating patients for colonscopy patients). the cons is the time commitment with a resident salary and that second year will not necessarily increase your salary potential in pvt practice. When you start earning real money afterwards the biggest advantage is the confidence in your dentistry, you will still have to learn the managment aspect, insurances, etc. But in general your speed and comfort level will allow to do more from the getgo not much of a learning curve.
One last thing that will factor into the decision is what the nature of the program, I dont know much about AEGD's but most GPR's are either VA based or atleast associated with one. Mine was 100% VA without dental school rotations (except for 2weeks of Peds, 2weeks of oral path, and a month of OMS). We did not do any ortho and had minor exposure to removal of impacted thirds (almost all of the veterans had them removed while they were in the service). I know some programs (I think Wake forest) will have you rotate in every department for and follow patient tx to completion. Ours was mostly pros, perio, rest and endo with implants being the highlight as we can do as many as we can txpln (place and restore). So that should also factor in your decision, some one yr programs are surgically oriented others are your bread and butter restorative/pros.
The bottom line is 2 yrs vs 1 yr is just one issue in picking a gpr/aegd.