We use Auth.net with one of our clients who processes an order about every 5 minutes around the clock. They started with LinkPoint which was horrible (bad support/high failure rates), and Auth.net is like a vacation in comparison.
Can I ask approximately what your client's failure rate is with Auth.net? This is a problem we're struggling with - out of 10 different payment attempts, we get maybe 1 successful payment (yes, some of the attempts are bogus, but that still seems pretty bad). It might be worth switching to Auth.net or something else, but the only reason would be the failure rates, and that information isn't very easy to find.
Failure of what? legit transactions? Are you saying that there are times when someone enters data that you know is correct and it still fails you?
That should never happen.
If you have full AVS checking, you might hit against the incapability of most users (quite understandably) to type in their address exactly the same way as on their credit card bill. For this reason, we (at my previous start-up) disregarded the address part of the verification (but still required post code and CCV2). Address failures aren't a good indication of fraud, since most legit users will mistype their address.
Well, the payments seem to fail for every possible reason imaginable (and many of the error messages aren't very descriptive), so it feels like death by a thousand cuts. The problem is that we're new to this game, and reliable information seems surprisingly difficult to find. Maybe it's perfectly normal to see 9 out of 10 people entering bad information or carders trying out numbers, but that seems high to me, and tech support has been useless.
We'll look into what AVS options we have available, and I'm also reading through the Protx link you posted.
This is a bit lengthy to debug via HN comments, but feel free to chat me on IRC (freenode), where I hang out as (predictably) swombat for a chat about this, I might be able to help in figuring out what's going on since I've implemented 2 such systems already...
