Pros and cons of Lower Jaw Surgery?

The symptoms that you are describing are extremely common and are frequently associated with one another. The answer to your question about the pros and cons of having a mandibular advancement can only be answered by the surgeon who is performing the surgery, based on your surgeon's personal outcome statistics. There are many different types of complications, and it is important for you to know that there is a vast difference between you, the patient, having a 1 to 2% chance of a major complication such as having permanent numbness or needing revision surgery, and a 5 to 10% chance of having a minor complication such as a low-grade infection that clears up within a week after surgery.
The scientific literature is full of studies about every conceivable complication associated with orthognathic surgery that could possibly be imagined. However, what is most important for you to know is how many procedures your surgeon has performed. It doesn't matter if your surgeon has been performing mandibular advancements for 20 years, because if they are only performing a few number of these procedures per year, they will not have much experience, they will not have made mistakes (and, hopefully, learned from their mistakes) and they will not have a vast body of personal statistics that they can quote from regarding their results. Ultimately, this is the information that you, as a healthcare consumer, will want to know. You may also want to see their before and after results, read reviews about your surgeon, and speak with other people that your surgeon has operated on of the same age, same gender, and the same facial structure as yourself to have a better idea of what you can expect. If your surgeon is unwilling or unable to provide you with this information, I would think twice about that surgeon.
My recommendation is to choose your surgeon wisely.

Jaw surgery with a mandibular advancement can permanently improve your facial profile, jaw line and the way your upper and lower jaws come together. The benefit is that the results are dramatic and last a lifetime. As you mentioned, the recovery can be involved and requires you to have a special diet for up to 6 weeks. And, there is a risk of permanent numbness in the lower lip and chin. This happens to some degree in up to 10% of patients. Your individual risk depends on age, technique and the planned movement of your jaw. Many patients who have some numbness after the surgery still report that they think the surgery was worth the risk because they are very satisfied with the overall outcome of the surgery.