Actually you couldn't be more wrong. The Sr16 is actually taken from real drums. You can even program it so it's so it's not dead on the beat (forget the name for the term right now, basically the same effect if you take a metronome and tilt it) If you take the time you can program it to do just about anything a drummer can ( short of responding to you in real time) Also it's inexpensive at 140, and easy to program. You can learn how to program a whole song within minutes of looking at the instructions.
I've recorded several songs with it. I've always got back "whos the drummer? Drums sound great. Or I wouldn't have known it was a drum machine."
Of course if you don't have a sense of what would be good drum part for songs, or how to mix it you wouldn't get that effect in a recording.
As far as the metronome thing, I think you are wrong on that as well. Metronomes are boring as all hell and don't get people into the beat so much as annoy the hell out of you. I can stay perfectly on time with a drum machine and actually have fun. I can stay on time with a metronome and want to throw it across the room after a few minutes just for being annoying and unmusical.
As far as making a pulse instead of beat that would dictate a groove, all you would have to do is program a simple loop with just a bass drum. there you go just like the metronome, without the annoying click.
To me it makes sense to develop your time center with something that at least sounds closer to what you are going to actually be playing with in the future.
I could see a metronome for someone who plays in a musical act that doesn't have purcussion keeping time, but if you are playing in the typical bass, guitar, drums band... I see no reason why a metronome would be superior.
whatever about the recording part, based on what ive heard, most dont sound as good as the one you mentioned...i was saying that most sound pretty fake, i didnt say all of them.
and as far as practice goes, you probably think you can hold a groove better with a drum machine...thats exactly what i was saying...they seem easier to play with cuz theres so much going on, it ends up hiding your problems. i think learning to play with a metronome is something you do before you start jamming with a drum machine. there is no doubt that a metronome is much less fun to play with, but when your practicing, fun oftentimes isn't what your striving for anyway.