Agree w/ Lilysmom. I also have mixed appliances, all different brands, no noticable difference in the ss.

Why would you get electric over induction?

Also are you stuck putting your cooktop in the island? It's usually one of the worst places to put it.

I'm going through this process ... and i've come to the conclusion that I don't really care. I think mixing and matching makes the most sense. Builders tend to think "streamline the look" and want to have all one brand ... but I think it's overrated.

What's underrated IMO is having all highly rated appliances, regardless of brand, that fits what you want to do. "best tool for the job" as lily'smom said.

I think most stainless matches to a degree. I don't think i've ever looked at pictures and thought "they don't match". What does seem to make a slight difference is making sure you have somewhat matching handles ... but even then.

As long as you don't have SS and mixing Samsung's dark SS. That still would work anyways, to me.

As an example, we're going with Therm range cooktop, single wall oven, Bosch speed oven in island (due to kitchen restrictions - i'm fine with this anyways), Electrolux Icon all fridge/freezer combo and Therm dishwasher. So it's kind of a range of appliances ... but it's gonna work out!

as for your specifics, I don't have any of it but I do have some comments:

- from what i've read lately, the island cooktop, downdraft and blower sounds like a great idea and looks awesome but it's wrought with potential issues. Have you really thought through the concept fully?

- why electric but not induction?

- I went speed oven because I personally don't like the look of microwave with trim kit to vent ... that's me. If I need my panny mw I can whip it out temporarily and then store it afterwards.

- if everything is installed well your kitchen will look awesome ... I think a kitchen that's not planned out well and installed well will be questionable - even if it's filled with high end stuff.

good luck