@Bruce Johnson would the Varethane Ultimate Water-Base Polyurethane be a good choice for a maple neck? Also does it need need to be thinned if I want to wipe it on? How many coats would you recommend?
Yes! Varathane Ultimate is an excellent finish for maple necks. It can be wiped on, just like Tru-Oil, right out of the can. No thinning needing. How many coats to put on depends what type of finish you want. For an "oil" style barely-there finish, one or two coats followed by light scrubbing with #0000 steel wool. For a thicker gloss finish, maybe 4-6 wiped on coats with some gentle level sanding between coats to see when it's fully filled and smooth. Then buff it up to a full gloss.
One warning: Varathane Ultimate is completely clear; it does not have any built-in amber tint like Tru-Oil and most oil-base finishes. If you put it on plain white maple, it will remain plain white. Most people like some tint on maple. If you want a tint of amber (or any other color) you have to add it to Varathane Ultimate.
If you want a nice warm amber tint, like what Tru-Oil does, and don't want to mess around with adding tints yourself, then I recommend using Minwax's Oil-Enhanced Water-Base polyurethane. Same easy application as Varathane Ultimate, but the oil-finish look is built in. It dries hard in a few hours, can be put on thin or built up and polished to a high gloss.