The main difference between line-in and mic-in is another gain stage. The real question is "do you need more gain?"
If you tape "loud music", meaning typical amplified rock bands I would say try Line-in, and you will probably get a strong enough signal. I have relatively similar gear, and that's what I do. Running Line-in with the gain cranked up is fine.
If you try line-in and have the R09 gain cranked up to 30 (max) and your peaks are still low, then I would say it's time to switch to mic-in, with the switch on the back set to "Low". If it's really quiet switch to "High". This will typically happen in quiet acoustic sets.
In my experience, I would rather run Line-in with the gain cranked up, than switch to Mic-in and have to turn the gain down to something like "5". I can't explain it, but I think when I have the gain turned down below about 10 it's just not quite as sweet.