OK, first good reason for applying inland is that your wife is non-visa-exempt. I don't know if she'd have to apply for another visa to come to Canada if she left being that she has a work permit - I guess it depends on whether her work permit is also a re-entry permit. It should say something about that on the permit itself. If it doesn't, you can contact the Call Centre but be aware that you'll likely get three different answers if you talk to three different people there - and none of them may be right. They'll tell you anything and they are not interested in helping foreign nationals stay in Canada. Unfortunately, in spite of all the rhetoric about "family reunification", those who work for CIC seem to be operating under an opposite mandate.
Secondly, the interview - if there is one - will be in Beijing and, you're right, she'll have to go when they request her to go. Not a good idea to have to postpone an interview. The good news is that it's very possible the interview would be waived - you can influence that by providing lots of solid proof of the development of your relationship and the genuine nature of it (meaning it's not just about your wife being able to stay in Canada). But there are no guarantees.
In favour of outland, though - processing through Beijing is very fast . . . only 2-5 months plus another month-6 weeks at the Case Processing Centre in Mississauga to assess your sponsorship application before the ap goes overseas. So it could be done in a matter of only 3-6 months if everything is straight-forward. Don't let a few extra pages to the application make the decision for you.
Really - you could go either way if yours is an obviously genuine relationship with no issues that will complicate processing. It will take longer for inland, because they're not even going to look at the application for at least 6 months - but because your wife has a work permit already that's valid for the next two years, there won't be any issue with her first stage approval and the rest of the process shouldn't take any longer than another 6 months - maybe even less. Depends on how fast they get the background checks back from her country - that always seems to be the big delay with inland aps. In the meantime she has status to be here, to work, etc. Aside from the appeal factor, it seems to me that it would be a lot less complicated for you guys to apply inland - even though, ultimately, it will take longer. But you haven't told me anything that makes me think there'd be any reason they'd refuse it - so even the lack of appeal rights doesn't seem to be a huge issue.
I think if I was in your situation, I'd apply inland . . . unless there's some issue like children left in her home country or a past criminal offence that might complicate things, I think you'll probably see finalization in about a year - certainly before her work permit expires in 2012. If she was refused inland you could re-apply outside - it's just that if, in the meantime her temporary status expired, she'd have to leave Canada.
