What to choose: freeware, shareware or software?

This question seems appropriate for programmers as well as for startups A few years ago I've developed a program that has a steady group of users. It became quite popular and now we have close to two million downloads on Download.com.

At first I provided the application as freeware to reach as many users as I could, but there is server costs and of course it would be nice to receive a bit of money in return for your effort.

I'm looking for a way to gain reasonable revenue from my freeware application, but still make a bit of money. Here's my experience so far:

Xacti : Low revenue and it took me a lot of emails to eventually get my money.

OpenCandy : Friendly, revenue is ok, good online overview of your downloads.

InstallMonitizer: We're testing with them right now, revenue seems higher and a referral program.

Another option would be to switch to shareware (let's say 30-day trial based), but I think that would cost me a lot of users. The offer screens are harmless in my opinion.

What do you use for your software (opensource, freeware, shareware)?

What are your experiences so far?

I am a passionate Open Source user. I even build software myself, if necessary.

I never use software which labels itself "shareware". I used shareware approx 2 times the past two years. With the term "shareware" I always feel it is something weird, probably installing trojans on my system.
Better I like the term "Demo". I am not sure why, but I have downloaded much more Software labeling itself as demo than "shareware".
Of course, this is highly subjective, but I feel like this. Probably others do feel like that the same.

I sometimes use freeware. But to be honest, i am not a huge fan of software which is free and I cannot look into the source code. I mean... how do they make their money? Installing something weird on my system?

You see I am a bit paranoid. My option (when open source is not avail) is to go to a serious website, look at the imprint and think if this developers look good or not. No name and just a PObox? No party.
Then I am willing to pay. I have never used Candy or similar stuff, except the Android Market and Mac Store. Actually I am willing to pay the devs directly and get my software license straightaway.

Another option I like is a reduced free version and some features enabled when getting the pro version.

Hope that helps a bit!

Cheers