That's good that you're taking ownership. Most guys around here just go out of business and then start another company with another name.

If the issues with reliability and user-experience were spelled out and said issues are exactly what you mentioned would happen, I would feel less responsible than if I installed a solution that I look back on now and say "Yeah...that solution kind of sucked and I probably shouldn't have put that in". If the latter is the case, I would give the client a break on something new but that's just me.