Hi, I went through a similar process earlier in the year and decided to buy a Fox Sailing Knife (links below) I looked at the Myerchin knives (very good quality) and also separately bought a Marlin Spike from them (again superb quality). For me the difference was in the size and blade, I wanted a combi blade (I know they're not universally liked, but for rope work they suit me) along with a reasonable length blade to give a good length of both the plain and combi edges. The Myerchin knives are very good quality but tend to be either plain or serrated.
As far as Marlin Spikes go, the Fox is superb, the separate Myerchin is also superb, leading me to believe that the spike on their knives would also be just as good.
The links below give details on the Fox knife in blue and in silver (the silver one is from Leoneshop.com in Italy, who give first class service, and if you go to the boating knife section there are several different makes and a number of Fox variants).
The bottom link show a German Navy knife with Marlin spike, I also picked up one of these as the blade is non-locking and hence a legal EDC in Europe (it means I can take it ashore without any worries). If you were to go for the German Navy version, do ensure that you find a genuine Fox as there are a number of cheap reproductions around that just do not have the same build quality.
http://www.heinnie.com/catalogsearch/result/?q=fox+sailing+knifehttp://leoneshop.com/en/sport_and_hunting/nautical_fishing_diving_knives/boating_knives/fox_sailing_knife_233_silverhttp://leoneshop.com/en/sport_and_hunting/nautical_fishing_diving_knives/boating_knives/fox-sailing-bundes-wehr_knife_230The knives in the links are available in most countries but also both the companies in the links (Heinnie Heynes and Leoneshop.com) give superb service and will ship globally on request.
Good luck and please do let us know what you eventually choose - happy sailing!