Ensnaring Bridge is cute, but it is not a good card. It's got terrible synergy with Mind's Eye, your single draw spell, and it means you need 2 Dreadnoughts to win. All that this does is kill aggro stuff. Not exactly a noble goal in a Tog and Combo filled format.
Ensnaring Bridge doesn't interact with Mind's Eye as much as you think. Taking into consideration that drawing a card is totally optional makes the two cards worth playing with each other. I also find myself drawing cards but playing my entire hand which keeps the interaction with Ensnaring Bridge to a minimum.
As for your other points, mono-brown MaskNought (well to be fair, ours had Welders) was the first thing we tested. And it was awful. It just sat there and pooped out prison stuff, before eventually winning around turn 20, the few times in won at all. It just isn't an optimal win condition, nor is mono-brown really that optimal of a deck. It has a high tendency of playing a couple Tangle Wires, then crapping out and sitting there while your opponent goes off and wins. Trinisphere is vital, at very least.
I found myself playing a Dreadnought by the 4th or 5th turn and smashed face with it way before the 20th turn. I don't know what kind of build you were playing because I never had that problem. As for Trinisphere, very true, I will replace the Chalices with them. How many do you think I should run 3 or 4?