Hi Josie:

I usually mix my song at 44.1 Hz which I use for WAVs, mp3s, etc. I then use Sony Sound Forge to resample the song as a 48k WAV for video work. At 48k, it sounds exactly the same as the 44.1 version, provided that I actually tell Sound Forge to re-sample at 48k and not simply SET the sample rate at 48k without re-sampling it. I believe simply setting it to 48k without re-sampling would change the pitch.

In your situation, I believe you could use Reaper to mix down both a 44.1k version and a 48k version of your song. Section 18.3, page 343 of the Reaper pdf manual talks about the different settings for rendering a project. The first window under the "Options" section is the sample rate. You could try rendering a song at both 44.1 and 48k and see if they sound any different.

I was like you -- I bought Corel Video Studio 6 AND Sony Movie Studio Platinum 12 64-bit because I wasn't sure which I could work with.
I ended up really liking Sony Movie Studio Platinum 12 because it's work flow is so much like a DAW. In fact I know several people who use the Sony Vegas (the pro version of the same software) as their DAW because it's audio features are so good.

The rendering time of 2 hours you got in Video Studio seems very long. For my first several music videos where I used still photos instead of video the render time to an mp4 file was just about as long as the song itself, maybe shorter (2-3 minutes. For the Bob Dylan parody I just did, where I used video, the render time to mp4 was about 6-7 minutes for the 2:45 minute song.

But I am using the 64-bit version of the program and I have an i-7 processor and Sony Movie Studio also lets me use my Video card (that meets certain specs) to help in the video rendering-- so I think all of that helps with rendering time.

As to why video uses 48k, I thought I read somewhere that video uses 48k for audio because you can divide 48k by the common frame rates of 24, 25(PAL) and 30 and get an even number, but can't seem find a reference for that so don't quote me on that.

Good luck.

John