A question about short URL redirects

I use a 'short url redirect' on my affiliate links. I do this mainly because it's much easier to manage and monitor campaigns. I didn't want to risk my main domain/site being seen as trying to spam the search engines, so in early 2012 I bought a new domain, set it to 'noindex' and use that for the majority of my affiliate links.

So for example, I use abc.xyz/goto/allslots/3.asp for iPhone users, and then ..../5.asp for iPad users.

I see many sites using their main/domain for the redirects (within a folder such as /goto/), and attended a couple of seo sessions at BAC12 last month. It's all got me second guessing myself.

Would there be any benefit to using my main/domain instead of a seperate domain?

I wonder what your thoughts are on this?

Thanks in advance.

My 2cents: it doesn't really matter. I use my main domain with nofollows and noindex on the redirect path. Using the main domain might look better to users, while some external, unrelated short domain might scare some users. But this is only my own oppinion.