ASA5580-20 with IOS software

Does anyone have experience using an ASA5580-20 with IOS software? On top of that, using it as a headend for an Easy VPN solution? I am trying to figure out how many sites it can safely support, also are there any major problems with it? All of the documentation on Cisco's site only talks about using it with ASA software, but then it only supports Legacy Easy VPN and not Enhanced Easy VPN. In order to support Enhanced you have to run IOS.

Thanks for your time,

ASA doesn't run IOS, it runs ASA OS/PIX OS, so there's no selection
to choose from. Ask this question again on cisco-nsp@, this isn't
a 'product/vendor selection list'.