I went against my fabricators advice, who also recommended a 1/8" negative. I think they suggest it because it is easier for them to fabricate as they can be "off" a little, and no one will see it. As for the cleanability, I've had my 1/8" positive about 14 months now, with no issues whatsoever...

I have close to a 1/4" positive reveal. No regrets. I keep it clean along with the rest of my sink. I hate having places where gunk can accumulate (and fester) unseen until it's gross.

"His view is that if gunk does collect under a negative sink reveal it will be easier to clean there and if we miss a little it won't look bad at least."

I don't think a negative reveal is at all easier to clean! And with a positive reveal, you won't have to worry about "missing a little" ... you'll see it if you do!!

I have a 1/8 inch positive reveal and I really like the look of it. A negative reveal was out for me because, like linelle, I don't like the idea of gunk having a place to hide ... I get really creeped out by "hidden" areas. And I really like the look of a slight reveal better than a flush mount. I've seen a lot of sinks where they mess up the reveal completely, so I was pretty clear with my fabricator that the results were important to me.

I have a very tiny positive reveal. Its about 1/16" and appears just about flush. Love it. Any stuff is easy to wipe off.

I have a positive reveal and so far have been happy with it. I was leaning toward not initially, but our fabricator said that they would go with what the sink specs were...which was for a positive reveal. At this point, it's been easy to clean, I can see if there's "crud" so that it doesn't sit along the joining area.

I wish I had done a positive reveal but was one of the few items DH have input.
No problems cleaning the negative reveal but I think I like the look of the positive reveal in the end

I've had a positive reveal for 3.5 years. My fabricator suggested a negative but I wouldn't have it because of the unseen gunk. It still looks brand new. I don't really know what there would be a problem with. I wipe around with the dishrag every time I do my dishes and I clean it with the sink. I plan a positive in my bathrooms and basement kitchen too.

I haven't used my sink yet (still under construction) but went with a very tiny positive reveal because I have soapstone. Was told by soapstone sales guy that it helps not to bang pots against the counter edge when lifting them up out of the sink (and potentially chipping the edge). I don't know yet if that is true. If you plan to use cutting boards, etc with your sink, a positive reveal provides a lip for them to sit on (but you can just rest them on the counter edge, but water/juices from produce could run onto the counters).

A negative reveal reduces the available area of the sink but this could be negligible. A negative reveal allows the fabricator some wiggle room for error--literally!

A positive reveal does require some fabricator skill--mine isn't perfect. I did live with a positive reveal on my original sink--for over 15 years. It was fine. I have negative reveals on my bathroom sinks and I don't like how big they are--eat up too much room. If you go with negative, specify that you want them to be as small as possible.