RE: Older ESC's with 2.4 ghz
According to this RC Heli Magazine article (see link below), the RDS8000 has a frame rate of about 24ms. The DX7 has a frame rate of about 22ms (see second link below). Odd that this ESC works with the DX7 and not the RDS8000.
[link=http://www.rchelimag.com/pages/scopes.php?scope=23&page=2]RC Heli Magazine's RDS8000 article[/link]
[link=http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPM2731]DX7se brochure (see the standard DX7 frame rate under "Features" ) [/link]