Like you this is my “last” kitchen and am too retired. I see no reason not to mix brands to get what you want. Particularly cooktop and oven. I have Miele Convection/Speed/CSO ovens, wolf induction cooktop, Zephyr hood, Miele dishwasher, Subzero FRidge and Freezer integrated columns and a liebherr bar fridge in my open concept kitchen/eating space/great room. No issues. Some are paneled some are not. If I was going with a gas cooktop I would go with either Thermador or Wolf. as I need a low simmer (initial reaon I started looking at induction). From reading comments on this forum it seems gas cooktops may be MIele’s “weak link”. There is no connection appearance wise between an oven and a cooktop IMHO. Get what works for you. EIther will look great!
Q