I'm not an expert, but I do plan on having painted cabinets, although not shaker door, mine will be custom site built cabinets. At first I priced all wood doors, but my cabinet guy told me if I was positive I wanted to paint them that the MDF doors would paint out much better than solid wood. I don't see why he would be dishonest about that, the wood bid was more, which would have been more money for him. I'm going with MDF.

MDF has no grain to possibly show through.

If your maker lets you pick paint, I strongly suggest using BM's Cabinet Coat brand. They've recently purchased this brand and it is fantastic. It's specifically made for woodwork and trim, and dries hard as an absolute rock.

Having painted and repainted my cabinets a couple times, I can tell you this stuff is tough.

That's all I have to offer.

A factory finish uses catalyzed opaque varnish, not paint. It's much much tougher. MDF or furniture board is more stable with the swings of normal humidity. You will still get "beauty marks" telegraphing the join between the stiles and rails, but not between the panels. I've got a couple of pics I'll upload about what real wood does in winter. Let me find them.

LWO. I wasn't thinking. Of course, catalyzed varnish.

When someone site builds, how do they do that?

CEF, the answer is that site built and finished can't. It doesn't approach shop built and finished, which doesn't approach factory built and finished. Someone who is very careful, and cares to take the time, like you, can get a very good quality "home" paint finish on cabinets by doing the correct prep and using high quality products. If a production carpenter were doing the same, you couldn't afford his cabinets.

Here's what solid wood does in winter. Especially with no humidity control. The dark wood is a reverse raised panel, so the center panel is solid wood, as are the stiles and rails. The second door shown is a center MDF panel in a painted cabinet. What you also see in this example is that the joins at the stiles and rails are also pretty inconspicuous, but not invisible. It's because the swelling and contracting of the center panel also puts a bit of stress on the stiles and rails. Now, this is my premium cabinet line, (Dynasty) and this is after an entire year in my showroom with a bit more temperature fluctuations and humidity fluctuations that I would like. It's basically a warehouse situation, not someone's home.

And for good measure, here's what a solid raised panel looks like in my medium grade line. The glaze disguises most of the line from the wintertime shrinkage, but it's still there if you look closely. Also, this is the difference between a stick and cope door, and a mitered door. You will notice that the join on a mitered door is much more visible after a year's normal swelling and shrinking.

Wonderful comparison!
I've never worried about weather weathering -- you get me!:) I kinda like the worn look.

However, given the fact I'm making cabinet doors this very second on my MBR floor, I find this particularly interesting and gratifying. I'm using 1/2" MDF as my base, with the wood trim that will be on the doors 1/4" to bring my doors to 3/4". They fit my face frames beautifully!

I'm copying this door, but not mitering. I'm dong it square. I don't know what it's called, but the stiles run up and down the full length of the door, then the rails are fitted in between those pieces. For some reason this, along with another style I'm figuring out how to make just speaks to me. Wanna see? Oh - and I'm painting with STIX and Cabinet Coat! :)

/End ;hijack
Anyway, if someone thinks "site built" is better, I'm thinking it's fine if it's built there, but taken to a professional place to have them painted. Other than that, they're getting maybe not even my kind of job! [whisper] and I believe I've mentioned how anal I am once or twice. [/end whisper]

The OP has some good questions. How does one know the quality of the finish? Does this catalyst finish also hinge upon the paint? Or does the finish process negate that issue?

Hmm...so is there anything specifically that would make a Medallion/Schuler painted door stand out as far as finish compared with say a Kraftmaid door if they are both the same wood type and paint process? I hear/read the Medallion/Schuler's paint finish is really nice compared with others but am trying to figure out why. Any opinions are greatly appreciated!

I can't comment on Medallion, but I do have a painted Kraftmaid cabinet in my bathroom and all of the doors/drawer fronts had to be replaced within a very short time because the paint peeled off of all the edges. And they all need to be replaced again but I am too inconvenienced (lazy?) to call them. The paint on the cabinet itself has held up fine. The room is well-ventilated and I don't allow steam to build up in there. The doors/drawer fronts are solid Maple wood.