That's good and nice if you want to record your guitar sound already effected on the wet channel and have a dry channel on the other track but what you have access to as sound programming from the line6 amp in reason is more than limited. You can a sound patch, only edit the amp settings, change the amp all together or change the cabinet that's all.
The advantage to have a complete plug-in like version inside Reason is that you can edit all your FX and sync them to the song's tempo. Edit on the spot your distortion, chorus or delay while the song is playing. .. etc. way more versatile for my way of doing things.
I prefer to work in that fashion, but the direct monitoring I also use if I don't have access to my preferred way of working..
See you mate...