Last week on Ask This Old House (the episode which played in my area, I mean) they helped a homeowner paint her kitchen cabinets. The professional painter TOH brought in (one they've used on various projects) said he recommends against using oil-based in a kitchen for two reasons: 1) it yellows over time, and if you're going to spend a lot of time doing the prep and painting, you want your paint to stay true, and 2) the fumes are just too strong for a kitchen, a space which needs to be used sooner rather than later, and by various members of a family. He and the homeowner primed, used two - three coats of the (water-based) paint and then two coats of poly over. In our den we used (I mean, the painters used) Cabinet Coat on the cabinets, and it is different than "usual" paint. In our kitchen (on wainscoting) we used BM's (water-based) Impervo and honestly, I like its finish better than the Cabinet Coat. They've both stood up beautifully, although in all fairness the Impervo gets much more of a workout than the CC (I've four and two year-olds) and we scrub it on a frequent basis. No burnishing, no color wiping up. It's really great. Over neither did we put poly. Do check the Painting Forum -- there are so many smart and generous people there. Good luck with your project!

The back panel provides a good deal of the strength. It keeps the box from racking, that is, moving to form a parallelogram of the sides and the top/bottom. This is even more important on a sink base, as there is no top panel to keep the box all together. What kind of cabinets do you have, frameless or face-framed? The face-frame provides some of that anti-racking strength. Now, having said all of that, how big a hole are we talking about here, and how is it located? As I say, the panel is mostly there to prevent racking. You really only need a strip of the panel near the sides/corners to provide most of that strength. The more the hole is located near the center of the panel, and the smaller it is, the better.

my cabinets sit directly on the tongue and groove sub floor. There is a layer of plywood and a layer of linoleum (i think that's what it is) that ends at the cabinets. We removed another layer of plywood and 2 layers of vinyl tile. We had such a hard time getting up that layer that we decided not to remove the other layer of plywood and the linoleum. We put a layer of new luan down, then the vinyl planks. But it all ends at the cabinets, so I need to cover it somehow. Previous owners used a chair rail moulding. LOL Of course, they seemed to use that EVERYWHERE to cover up stuff they didn't want to fix. hahahahaha (I really dislike those people!)

I wanted a vintage-style, furniture-look in my kitchen so I also have the arched trim pieces on each side panel. I love the look and would do it again, but it does make sweeping more difficult, because debris gets stuck in the corners. I don't think the open toekick will make the kitchen look dated and, in my experience, visitors to a home don't notice things like that (toekick on one side not matching the fridge surround on the other side of the room). If it makes no difference to you--open is easier to keep clean.