You will keep losing hair behind the temples for years to come most likely even with propecia. You must plan on having more surgeries through the years if you are going to go this route. I had 100 transplants back in 95 hehind my temples to buff them up. Got on propecia, used Nizoral. Temples kept receeding and now have a little one inch or so field of plugs which look like fish hooks in my head. Worst mistake of my life.
Be honest with yourself about how much hair you think you will lose in the next 30 years. We cant count on cloning or multiplication until it comes to pass. There is no telling what problems mother nature may introduce to scientists there. I understand fiberblasts (scalp skin hardening into forhead skin) is a problem for early stem cell researchers. You will proboably end up getting about 1000 transplants over your lifetime if you are relatively young. Opt for a slightly receeded appearance to be safe, get a surgeon who does follicular units. Stay away from big transplant mills like MHR and Bosley and NuHart and find a Doctor with a great reputation. HairTransplantNetwork has pics of docs and their work. I implore you to consider just researching this site on maintaining the hair you have until you are at least 30. I wish I had.