Erick, yes, metal studs would be better in my eyes. I'm a union carpenter who works with metal studs on a daily bases. I wouldn't skip the top and bottom plates (called track in metal framing.) If I understand correctly you can just notch the top and bottom track around the area in question with your metal snips. I know you said you need the back of the drywall to be right @ 2", but I would just leave 1/2 inch on the notched portion of the "track". Notching a moon shape in the top and bottom track. This would make them 1 1/2" away from the pipe which is not going to be a problem!
BTW, metal studs usually come in 1 5/8", 2 1/2" and 3 5/8". What you should use is 3 5/8 as the others tend to deflect more. You should not have a problem building this chase. Good luck!
BTW, metal studs usually come in 1 5/8", 2 1/2" and 3 5/8". What you should use is 3 5/8 as the others tend to deflect more. You should not have a problem building this chase. Good luck!