At the moment the break chance on siege gear is much higher than it is on armour, weapons and as far as I can tell every thing.
Carrying construction materials results in at least one break every round. Every round I carry my construction site I pay out on its +2k cost.
I don't won't it to be lowered significantly but it does cost much more than it should. I have used cavalry at the same overall cost as my siege build and made money. While carrying the siege gear I have gone through around 210k this gen and I'm only 2/3rds of the way through. I had to borrow 100k to pay for my habit, at this rate I'm going to have to flog my looms to get through the gen using the gear.
Should be noted that I've burned 45k in 2 3 hours sessions and have only been using the siege site for 2 days, the rest of that money was killed by my construction sites.
My total eq cost with out siege gear is 2,265. With siege gear its 45,336. My old cav build was 52k and I made money :/