We have decided to replace the Natures head composting toilet. From the research I have done, these things retail for over $1000. I will list it on Craigslist.org and try to sell it for $500 which should be about the cost for 2 new full sized bowl marine heads. 
Of course I will need to find a spot for 2 new holding tanks and all of the associated plumbing as well as budget for it, but the admiral is totally in line with this idea. We have had head smell issues in the past on other used boats, and the thought of not 1, but 2, smelly heads is just not appealing! We will go brand new for both systems and build them right. (Add 2 marine heads, hoses, holding tanks etc to costs page)
UPDATE: December 31, Natures Head is Sold!! Now we have a big empty space….and more holes to fill…