Hey!
First, all this is about mechanical SATA drives. I could not get an SSD to work reliably through one of these converters.
I meant to write about this. Specifically, I have tried a few of these on boards with UM8886BF for the IDE controller.
A converter with a SATALink brand chip was a disaster, too unreliable to even fdisk/format/install DOS.
A converter with a Marvell chip (StarTech IDE2SAT2) works great but with one huge drawback--when the Primary Master is a SATA HDD connected through that converter, the native IDE CD-ROM connected as secondary master is not detected. Take away the SATA converter on primary and it works great...
I got one of those JMicron JM20330 converters from eBay. It works great and the IDE CD-ROM still works. On an MB-8433UUD-A this worked fine with the stock configuration. On a Gigabyte GA-586AM I had to back off the BIOS speed from PIO Mode 4 to PIO Mode 3 for it to work without corruption. More on that at some point in the future...
Finally, with Socket 5 or 486 or older boards, the IDE controller does not support bus mastering DMA transfers in the 'modern' way that the Intel Triton chipset introduced. You are stuck with programmed I/O. One of the biggest speedups for PIO mode is Read Multiple Sectors/Write Multiple Sectors. Instead of generating an interrupt for every 512 bytes, they can be batched into blocks of 1024-8192 bytes. In my experience SSDs do not support multiple sector transfers even when run through one of these converters, while HDDs do. So a mechanical drive may actually be faster, especially when a modern 1TB/2TB HDD has a relatively huge cache inside it vs. what would have been typical for these machines.
I've also heard people are much happier just using those CompactFlash to IDE converters. Less "conversion" going on since they are based on IDE. The lack of multiple sector transfer support applies there too though.
There are also industrial SSDs out there with a native IDE interface on them, I believe being produced new by a company in California. I can't find the link.