As somebody who has worked in the Storage industry for a “long time” I would like to recommend the following solution for all ATV flash Customers.
In the early days of Entertprise 2.5" SSD’s the Intel X25-E was considered the Rolls Royce of all SSD’s mainly because of the fact that it had the fastest SLC based Flash Memory with 250MB/sec reads and 170MB/sec writes. Back in those days it cost an absolute Bomb! Now however you can buy used 32GB X25-e’s for under $100 on eBay and they make an old ATV1 run like you have introduced steroids. Because they are SLC based, “Trim” is not required to keep them healthy and they should give years of life in the ATV Flash environment. All I would recommend you do is secure erase them using the Intel sanctioned method found here http://www.iishacks.com/2009/06/30/how-to-secure-erase-reset-an-intel-solid-state-drive-ssd/ before you install them.