@jaco Went 3-1 (7-2) for 2nd place with your list yesterday, swapping Confluences for Cities and Pyroblasts for Red Blasts on a because-I-own-them basis.
Two of the four decks I played against were heavy control decks. Welder is an all star in these matchups. He costs 1 so they frequently forgo artifact hate to leave in Misstep. As long as you can get some artifact, any artifact, into play, you can get your win cons.
I also got to do my favorite 2CM welder move: Activate Grindstone, maintain priority, weld out Grindstone for Painter. My opponent had to think about that one for a bit to figure out when he was supposed to cast his answer.
I did run into a bit of trouble with Dack Fayden. Normally, I'd wait until I had the win in hand, castable, and activate-able. Against Landstill, this was tough game one as I got Strip/Wasted turns one, two, and three. Game two, he cast three Force of Will, two Misstep, and two Mana Drain.
Daretti never did anything other than eating countermagic. Nevertheless, I really like the idea of him in this deck. All three abilities are relevant. I figure if you can land him, they're probably out of countermagic, so you can ultimate to get back the win condition they countered.
A couple people both online and in meatspace and online expressed disbelief at my playing Bob. I was actually a big fan of him. By my quick count, the average CMC of the deck is 1.35 and fully 25 cards (42%) are CMC 0. Given the lack of "answers" played in this deck, the information revealed to the opponent is rarely relevant. I greatly appreciated the additional card draw. Incidentally, Bob also dealt a considerable amount of damage to my opponents, including being lethal when I instead cast and activated a combo kill. I really like having the additional out against Null Rods and other artifact hate.
On the subject of a less-hateable kill, I've usually added a Tinkerbot to 2CM. Multiple times during the day, I had Tinker in hand but nothing particularly useful to get. I think I'd add it here.
It seems like most people consider it a black and white choice between Welder and Draw 7s. I'm not so sure that's the case. I'm going to try a Wheel with Welder - besides drawing 7, it enables more Welder shenanigans.