The Tascam has more features, but I'd never use them, I like the Line 6 because like you said, it's just a straight on riff recorder. And like you, and I'm sure countless more guitarists, I've forgotten more riffs I made up than I can remember. I like the Line 6 because I can just turn it on, and it'll only record when I start playing(or talking to someone...like myself
) it's a fully automatic recording device, just turn it on and jam. Then you can import the WAV files to your DAW. If I bought the Tascam, I wouldn't buy a recording setup, just some software. But it is still a cool little recorder, and probably would come in handy at a jam session with the guys just because you can fit it in your gig bag.
edit: BTW, I'm soooo happy you started a Recording/live gear part to this forum. Like the band Tesla said;"It's gettin' better everyday". Keep it up bro!