I assume you are looking at Miele 626x series oven. The Culinario H6267BP is a very good choice. There is a promo 600$ off at the moment till November 30th, see http://www.miele.com.au/domestic/cooking-baking-8-3219.htm. The flexiclip that comes with the oven is very handy and can be left in there in the self cleaning cycle. The perforated tray is also great for bread baking. H6267B is still a good choice, if you don't want to pay for pyro function. If you are set on Sirius brand, SL906 L850 is another option. Baffle filter works pretty good; I have one on my big whispair undermount unit. The perimeter extraction in SL907 may work fine. It will depend on your cooking. SL906 probably can extract air better, but it does not look as cool.

how2girl is right, ducted is better. Ducted extracts better and with less maintenance. But it might be difficult or impossible to do, for example in a two storey house with the kitchen in the middle so that there is nowhere for the ducting to go. suzineedsahouse is right, different people have different requirements and what is important for one person might not be important for another person. I have seen a house where a window beside the cooktop was enough for the owner (I did wonder how that works on windy or rainy days). Some people are happy enough with a non-ducted rangehood. Some people insist on a ducted rangehood and are willing to rearrange their houseplan if necessary to ensure they have space to install one. I have heard of people who have chosen commercial rangehoods for their home. I know of people who have a second kitchen outside in their alfresco area which they prefer to use for some of their cooking and sometimes even those have a ducted rangehood. (Btw as far as I know a gas cooktop only affects your choice in regards to how high above the cooktop the rangehood must be.)

HI Check out Whispair. We have one installed and short of it being on full blast you cannot hear it, even though the motor is within the unit. If you want a remote unit you have to make sure the ducting is done right, but the Schwiegen is very quiet. Cheers

Yes, but are you using the gap where rangehood was to centre, or the centre of the cook top. If you have cabinetry along the wall then you can hide the fact that the extractor fan/rangehood is not centre of the cook top. Or that is how it appears in your photos.