I have no personal experience with SSSA but have a friend who currently is going there, also for conversion purposes from a FAA license. I've been in contact with them but in the end chose a different school even though the price was higher. The reason was mainly that I've had my fair share of flying old, old planes during my initial training in the US and wanted to fly modern, up to date planes.
The reason why SSSA can keep low prices is in my opinion because their fleet is indeed comprised mainly of very, very old aircraft and stated quotes includes several hours in the C150, as an example.
Now, I am not saying that makes it a bad school or that your training will be subpar. I am just saying that I personally felt that it was worth paying a bit more to fly a modern fleet at a more well-known school.
Just my two cents though! Good luck!