Steve,
The only reason I am doing this (upgrading from 4.1.9) is because I needed to solve PCI compliance and using paypal was costing me about 40% of my business in lost conversions. And yes, my site needed a visual and functional overhaul too, so 6 years of 4.1.9 was 3 years too long.
X-payments required PHP 5.3 -- so upgrading from php 5.2 to 5.3 was a small journey in and of itself. Documented.
I own an x-payments license, and a VPS server, so my cost of entry was simply an SSL cert.
My gateway (Elavon) does not yet have an iframe solution, so x-payments integrated with iframe is the lesser of the evils. Bill Brewer is making CheckoutOne compatible with xpc iframe this week, so that solves the paypal callback issue... lots of reasons "this is the least evil way to solve the checkout".
Considering xpayments has been on the street for 2 years+ and version 1.0.5 has been out for months gave me false confidence that bugs were squashed and a large enough userbase to understand the challenges...
Didn't expect to be the first to make these discoveries!
