I was experiencing the same problem as you guys. First of all, I'm a hobby developer and not a multi-million dollar enterprise, so therefore I don't and cannot throw money at problems. If you're a multi-million dollar enterprise, this solution is not for you. Buy certified hardware and use certified software.
While I was already prepared for using SATA II for my Samsung 830 SSDs instead of SATA III (hardware limitation), I was not expecting SATA I. I'm not gonna sacrifice 50% performance, just because SAS 6iR negotiates extremely conservative speeds with non-certified drives (software limitation or unfair marketing strategies - decide for yourself).
I've been using these drives for years in SATA II environments without any problems. Also, I don't expect running them at the same speed in conjunction with the SAS 6iR. To me, it's just a form of unfair marketing strategy, in order to sell own, overpriced SSDs. IANAL and I don't know, whether this is okay in the US. But here in Europe / Germany, you can easily get *** for artificially limiting other vendors products, just to sell yours. There is no technical background for doing so - in my opinion.
Therefore, I've decided to share with you, how I've managed to run my non-Dell SSDs at 3Gbps instead of 1.5Gbps. No need for interposers or other weird stuff. Why would you need interposers for non-Dell SATA drives, if Dell's SATA drives are working fine without? Just software - the same way, Dell has limited your drives to run at lower speeds.
My setup: I'm using a Dell R410 with an integrated SAS 6iR, 4 drive hotplug chassis. Btw.: I cannot buy interposers for hotplug drive caddies seperately and would need to waste big money on them.
Here is a picture of proof: drive.google.com/folderview;usp=sharing
You will need a Linux environment - I have used CentOS 7. You will also need lsiutil 1.62. Fire up that utility, select SAS 6iR and enter option 13. Here, you will be able to set up a minimum and maximum speed for your ports, individually. Just set up 3.0Gbps as minimum speed for all your active ports, leave the rest at default parameters. Your result should look like this:
After a restart you can finally have fun with your non-certified drives at 3Gbps. No need for further hardware or further costs.