It used to have a 90-day free trial, but that's amended now to 60 days. I could speculate about demand for the product as it might affect such an initially tantalizing trial period.
You should be easily able to cache a RAID array. It's a lifetime license, so the single PC option is not a lot of money spent or wasted.
In my case, there are some options and constraints that affect a dual-boot system. According to the tech-support, one SHOULD be able to maintain SSD cache disks for each OS. I THINK they have to be on separate SSDs, and creating separate caching volumes for each OS on the same SSD could be a problem. In my case, I'm only using the SSD-cache feature for a single OS right now. But that shouldn't be a concern for the OP.
You can cache a combination of AHCI, RAID and multiple drives under a single SSD cache. Or the same combination cached to a common RAM-cache (or separate ones), or a combination of RAM and SSD-caching.
The SSD cache works with RAM-caching, which is also a nice feature if you have some extra RAM to use. I haven't upgraded to 2x16 32GB yet, because I seem to have plenty with 16. Some people with enormous tasks and data configure 128GB of RAM, and even use a single 960 Pro for SSD-cache. Definitely not a requirement for a single workstation or gaming system.
As to the SSD-cache again. You cannot measure its impact in benchmarks! But -- you can feel it after the cache loads up. This is because it fills the cache stealthily when the system is idling, and the results of a benchmark simply won't register. This will supposedly be changed with version 3.0. But there's no doubt that the SSD-cache matters.
The larger the SSD you use, the larger the block-size recommended, or you will begin to consume large amounts of RAM in overhead.
Ram-cache can be saved and prefetched through restarts or reboots. If you plan to cache a drive that has offline writes, you will run into trouble unless you only use session-specific RAM-cache that is not available for the next boot time, and obviously you wouldn't use SSD-caching for a drive that has off-line writes.
As for any real "troubles," there haven't been any except for a foolish experience with the offline write problem and another with dual-OS caching volumes on the same device. And I figure if you can create a dual-boot system that works flawlessly with prudent caching choices with no problems and only the desired benefits -- "it's good."