Hi SgtPepper,
For what it's worth, we've been running a production cart site for years on GoDaddy's Economy shared linux hosting, using PHP-based cURL strangely with no significant issues (though using a different SSL payment module). Perhaps we are an exception to the norm.
Be sure to set your cURL proxy: http://proxy.shr.secureserver.net:3128
I did also have to bump our cURL timeout to 30 seconds since the default of 8 seconds or whatever had proven to be too tight for both the proxy connection and transactions, which (either) can be a little slow at times. You may want to look at adjusting this timeout value to suit as well.
A lot of the payment module operational concerns also depend on how the modules handle (and report) any cURL responses and/or error messages to the End User (and Admin for that matter). While I haven't looked at the Authorize.net mod specifically, having written a couple of other payment modules, a little bit of good error checking and reporting goes a long way.
Hope this helps some.




