We are not familiar with iDevAffiliate; however, we do offer our own, basic Affiliate tracking service that is built right into our cart service:
http://www.e-junkie.com/ej/help.affiliates.php
If you wish to use a third-party affiliate service, that would probably depend on having their tracking code in your E-junkie thank-you page in order to track actual sales conversions. Note that PayPal Website Payments Pro is the only payment processor we support which displays the thank-you page automatically after successful checkout; regular PayPal standard and all other payment processors only provide their own checkout confirmation page with a return/continue link, which the buyer must click manually to reach a thank-you page that would have your conversion tracking code, and if payment was not completed immediately, then your thank-you page would normally not even be displayed at that link at all.
We do not wait for completed payment if you are using Redirection to show buyers a thank-you page on your own site URL:
http://www.e-junkie.com/ej/help.redirection.php
You can also bypass waiting for PayPal to confirm completed payment and just offer our thank-you email and page link after checkout regardless; however, you may not want to offer your product-download links that we normally provide in the thank-you page unless and until payment is indeed completed. Furthermore, either of these approaches still depend on the buyer clicking that return/continue link manually, in order to leave the checkout page and reach any thank-you page at all (aside from PayPal Pro as stated earlier).