Well, 30 year old carbon steel hinges didn't last that long. Two of them snapped off while I was opening the lid up.
I can definitely tell the weight difference (maybe 75lbs to 100lbs?) when driving around topless.
I've got some stainless steel angle brackets and stainless steel hinges coming in to fab out some replacements. The hardware fer this alone is about $80 (bolts, washers, nuts, hinges, brackets).