My personal opinion is that if you don’t do it right in the first place the longer term effects can be devastating.
Over the last few months I have been trying to resolve an issue with costing at one of my customers where another NSC implemented badly from the start. So far they have paid us more in support than how much it cost them to implement in the first place.
My recommendation is to reimplement but for one reason or another they are not in a position to do that at the moment.
This is a proven result of a bad implementation in the first place.
I am not saying that you will implement a bad system, I am just trying to show the smallest problem at the start of an implementation can end up in an expensive solution to resolve further down the line.
Take the time to do it right, and correctly in the first instance and the customer will love their system, do it wrong and they will have a bad tatse in their mouth and may end up leaving you.
Its a thin line to walk Cost/profit. But trust me it will cost you less to get it right now, than fix it 6 months to a year down the line.
Anna has given you a good path to follow.