Are customers more likely to buy a plugin with a monthly subscription or a one-time higher price?

As a heavy personal/business user of WordPress I would more often instantly purchase an outright license for a Plug-in as opposed to a monthly subscription fees.

Here are some of the things that makes me decide against month-to-month subscriptions for a plug-in:

• Not having an 'unlimited' site license (like say the Thesis Theme has, even though it is a theme and not a plug-in).
• If license is strictly based on the domain, I many have many domains, the licensing fees becomes too much of a monthly investment.
• Not having a trial period, especially in cases where to truly appreciate the benefits of the plug-in (e.g. SEO plugin), you would need time
• Not having a 'free' version (granted with certain functionalities not provided for)
• Not being able to transfer the license (if i wanted to sell my WordPress blog)