My GMT Pepsi for a Seadweller?

[jg2525]

My local jeweler where I bought my 16710 a couple of years ago has a "P" serial sea dweller that I can make a trade on. Here is the story, the GMT was my first and only Rolex to date, and recently I have been wanting something more along the Sub line, and have liked the SD 16600 as well. The SD is in exc condition with full box and papers, which my GMT has as well. My GMT is a "Y" serial, and based on what I have seen here, this serial may be desirable based on the lug holes and SEL's, I would like opinions on that as well. Keeping one and buying the other is not really an option for me, so, comparing these two specific models and serials, is there any compelling reason to trade or not to trade based on your knowledge as far as one being desirable more than the other because of "fill in the blank"? And if the consensus is whatever I like best, that is fine as well. By the way, the trade is pretty close to even money. Thanks all...