Going to launch a flyer print-ad. Anyone have response figures on A4 vs A6 sizing?

EDIT: PLEASE SEE POST #7 AS IT HAS BEEN UPDATED TO REFLECT SIZING IN STANDARD US MEASUREMENTS

Hi everyone. Hope you are all doing well.

Soon I will be launching my e-commerce store. Among some other forms of marketing that I will be looking at doing, will be print advertising.

I don't mean in the local paper, though. I will be having the print adverts designed, printed and solely distributed to homes. I may also hit up city train stations and hand out flyers to passers-by.

I am hoping I can turn a decent ROI with print advertising as it is so easy to scale it upwards massively. So long as the initial tests return a positive ROI and assuming the test population is a true sample of the real population.

Needless to say, I'm fairly excited about going forward. I've got a great designers on hand and I intend on making the print advert fairly minimal.

The item on sale is an Android tablet and so the focus will be on designing the advert to show off the tablet and it's features. It's going to be fairly minimal, in terms of design.

Now, the question is: What can I expect to see in terms of A4 vs A6 response performance?

Ideally, someone who has tested the exact comparison above would be an ideal candidate to reply. Failing that, anyone with direct mailing experience is more than welcome to reply. It might turn out a good experiment if we choose to follow along with it and see what the responses will be like.

Let's assume that the A4 / A6 will have the same content on them.

I know my costs for A4 and A6 print ads. Effectively, since A6 is half the size of A4, it is also half the cost. However, I have a feeling that just because the A4 is twice the cost of A6, does not necessarily mean it will receive a 2x higher response.

When you look at them out in front of you though, the A4 really has a lot of room for a big, clear image/design. It looks a lot bigger than the A6 (which it is) and so I assume the response would naturally be higher for the A4 - but by how much?

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Off-topic: Anyone advertising/promoting their business or anything using flyers / print ads? How is it working out for you? Do you have the advert dropped into mail boxes, or do you have them handed out to people in public places?

If anyone has worked with consumer electronics - what type of response do you get on similar print ads?

Thanks -
Chris