Very nice, I too use Photomatix & ACDSee.
I feel as if the picture is tilted to the left, as if I'm going to fall over in the shot. A little more gray in the shot would have given it a deeper effect, the trees outside look as if they are right against the windows and or painted in cardboard and pasted to the windows. Lost some depth under the workbenches too, I would have like to seen what's on those benches, would have made me feel as if I can reach out and touch them. The anvil on the left would have made for a great part of the picture, I would have brought that into the frame more.
Great stuff, I've not done much with sepia in HDR, so bold step, I really like the shot, stone is by far the best thing to shoot in HDR in my opinion. And this room has a lot of that. Please post some other shots, color, black and white, grunge etc. lets see what else can be done.