I chose not to go with a fabric shade because of your concern. When the weather is nice we frequently have doors and windows open. I use my range vent religiously, but they is still just dust. I dusted my metal shades today and they were pretty gross.

How much kitchen grime builds up on your kitchen surfaces (like the tops of picture frames, ceiling fan blades, current light fixtures) and how quicly does it accumulate?

I decided against any light with fabric because my kitchen seems to get grimy and I know it would bug me if I couldn't clean it properly.

If your current light fixtures stay clean without cleaning them for a few years, then why not go for fabric.

Also, can you replace the fabric part if you need to in a few years?

Thank you localeater and tricia257 for your input.
Currently we get a lot of grime because our kitchen is not vented properly. When we do the reno we will be installing a microwave vent. However, I am still a little concerned with the possibility of grime.
I will look into possible replacement of the fabric part but I think I might be looking more into a different type of light fixture.

With a MW vent, you've got pretty anemic ventilation. Skip the fabric. It will need cleaning in no time. Or else explore putting in a real external vent.