Basically a pyment can be dry, semi-sweet, sweet or dessert. The honey character may range from subtle to intense and may or not display varietal character. It should however present with varietal character or nuances if the honey varietal is listed specifically in the ingredients. The grape character may be subtle or intense depending on varietal and/or blends thereof. If the varietal is called out in the ingredient list there should be some indication/character imparted to the pyment from that specific grape varietal. There may also be slight or pronounced diacetyl character from the wine undergoing malolactic fermentation. In reds it would be less pronounced than in a Chardonnay pyment for example. Oak character may also present and should be indicative of the oak used (i.e. American, Eastern European or French). Astringency, acid and phenolics should be in balance with the grape varietal and amount of honey used. Color will generally trend toward the type of grape used so it's important to be mindful of the type of honey you're going to use. So if you're making a dry Chenin Blanc pyment, using Avocado, Buckwheat or another dark honey is probably not the best idea, whereas the color contribution of the honey will not be as easy to discern in a red wine pyment (Petit Sirah, Zinfandel or Aglianico, etc.) but still should be paired to maximize the contribution and blending of complimentary flavors and aromas.
There is no percentage that dictates whether a wine, pyment or honey fortified wine in the current style guidlines, however, the grape and honey should be complimentary in aroma, flavor and balance. Much like a braggot a strong honey may dominate in a lighter beer style, while the grain may dominate in a darker beer style, the same can be said of a pyment. My rule of thumb is that if the grape must has been fermented to completion and the honey is added and a second fermentation is made, you have a honey fortified wine. If the honey is added to the grape must (skins, stems, seeds, pulp and juice) and fermented you have a pyment (or if you use concentrate from a kit, etc) If you ferment a mead and add grape juice in secondary, that's still a pyment as the main fermentable was the honey in primary. If you add finished wine to a finished mead you have a mead with wine added. You can go many ways with this and frankly arguments can be made in any direction, and there are many many ways to do this with no one way being right. Bottom line is that as long as you have good representation and support of flavors, varietal nuances and characters pyment is a good moniker in my book.
Cheers,
Oskaar