We have sold a lot of HD's lately and not one single complaint from any customers, even with a bed with not a whole lot of weight. There is absolutely no difference between the SD +2 and +3 as far as material, just the amount of the arch is the only difference. The amount of load for each one is the same. If you are carrying around 300lbs or less, get the SD's.
The HD's have some thicker leafs but also the difference between a +2 and +3 on an HD is the same material grading all the way through, its just the amount of the arch. We recommend the HD's if you plan on carrying more than 300lbs on a constant basis. For folks who want to go beyond 500lbs, we can get them custom made to accommodate that (up to a point). Custom orders typically take 4-6 weeks.
We usually keep stock of the SD and the HD's on the GEN2 since those are popular right now and have sold quite a bit this year. Currently during our sale this month, we ran out of stock and the SD's are going to take about 2 weeks before we get stock again, so please take advantage of our sale now to get a great deal and get on the list.
https://www.fordraptorforum.com/posts/1287020/