Is link to Amazon on sales page a "leak"?

Yes, that is a leak.

Anything that directs the vistor away from the page without you getting a commission is a leak. At least that is my understanding.

Leak for sure, it's like comparing oranges to apples. Do you want a 4% commission or 75% commissions from clickbank. You want visitors to focus on your offer, and not stray from it.

There's a big different the the commission percentages so I would definately stay away from that one.

And to me.

Yes. A couple, in fact.

You can write to the vendor and ask him/her please to provide a "ClickBank-only" sales page, for affiliates.

The reality is that this is probably a vendor with no serious affiliates at all, who is perhaps using ClickBank largely as a processor and isn't really geared up for affiliates at all. There's nothing to stop them from continuing to use that page for themselves, of course, if they want; but if they want affiliates, they perhaps need to provide a sales page without "payment leaks".

The other possible work-around (which I wouldn't try, myself) is to do the same thing yourself by replacing the vendor's sales page on a site of your own, with the payment button linking directly from there to the vendor's ClickBank order page. Note that you need the vendor's permission to do this, and you won't be setting your affiliate cookie on your prospective customers' computers. (You'll still be paid for the people who click on your link and buy, but not on anyone who returns later to the vendor's sales page rather than to your own, for example after doing a Google search for the product, or whatever. If you're a list-builder and sending email links regularly to your subscribers, I don't know how much that would bother you? It's a huge work-up, anyway, of course :p ).

The bottom line is that if you want to promote the product, you either have to take a chance on losing some sales or discuss it with the vendor and come up, one way or another, between you, with another sales page. :rolleyes:

For what it's worth, my guess is that - other things being equal - only a small minority will choose to buy it on Kindle rather than as a PDF, so the downside is perhaps limited. I might be wrong! But if it were something I really wanted to promote for some specific reason, I wouldn't necessarily decide to "stay away" because of this. Just my perspective.

(You can ask the vendor what proportion of the sales from that page go to Amazon, of course, but you'll effectively have only their word for the answer).

The commission percentages are not relevant to this point, because customers choosing the "Kindle" option wouldn't even have your Amazon cookie anyway. You'd effectively be losing those sales completely.