My recommendation? If you always send your razors to the same person, contact them to ask what their finishing stone is, and get that. You already know what that edge feels like, so it removes guess work if you'll like what you get off this stone or that.

An 8k edge should shave fine, but I find the edge from most any synthetic is a touch on the keen/harsh side. Usually that only lasts 1 or 2 shaves, then it mellows out and becomes more comfortable. Or it can be taken care of with a really good stropping.

If you're just looking for basic maintenance, a barber's hone can be hard to beat. Especially if you're looking for a minimum cost option. 30 bucks for one in good condition, 4 to 10 light strokes every few weeks, and your edge will be good indefinitely.