Your case is another illustration of the complexities of this darn disease. Every patient is different and we get different suggestions from different practitioners. Here are some thoughts:
1. It's obviously a good idea that you are talking with surgeons. There are plenty of patients with Gleason 7 who have had both open and robotic surgeries with success, including nerve sparing. But, it's not just the 7 that counts, it's obvously the whole collection of stats including your other health issues.
2. With your weight issue, brachytherapy is likely a good choice...can't say whether traditional or HDR is right but...just google "brachytherapy overweight" and you will get some good evidence that suggests this protocol is a good option for overweight men.
3. Seeds may be yesterday for your particular doc, but not so with many...including mine. Zufus preaches multiple opinions and I think he is right. You are near Dattoli, why not go there and get another opinion. They are well thought of.
4. With your combined stats, the radiation docs will probably suggest exteral radiation in addtional to brachytherapy either with traditional seeds or HDR. It's not just the 7, but a combination of things that are considered with that recommendation indluding the % of nodes positive, PSA velocity and the fact that something was felt on the DRE. That means the tumor(s) are likely closer to the edge of the prostate, lessening the chances that brachytherapy alone will do the trick...hence the need for additional radiation.
Hope this helps...please let us know how you progress.