I think it goes without saying the customer with the mats and request for the synthed item must adhere and acknowledge the risk that comes with any item being crafted. There is always a possibility of a break/crit break.
I slowly see this thread subject derailing off subject to what good tipping etiquette is for the service of those who took the time, money and effort to level a craft up all the way, and I most certainly agree 100%.
However, I like the idea of this synth menu idea because with the current system now, there is absolutely zero obligation for both parties to adhere to their agreements. We all know 99% of the players in this game are not trustworthy. We see TONS of threads on these forums about so-and-so stealing "X" item or so-and-so ran off with HQ when he agreed to trade it, etc. But with a simple menu with options for trade agreements, terms can be met on both ends before any action is taken that cannot be undone. It's protection for both the customer and the crafter alike.
For those who find the lack of trust to be a problem with this, you have to remember that you the crafter have complete control over the terms and agreements. You tell the customer the conditions, policies, and terms of any circumstance that may happen when they hand over their mats.
In short, if they break, it's the customer's loss and risk, if you NQ or HQ it, you can agree beforehand if they pay gratuity or not (after all they're using your hard earned service). There's already enough trust issues with people in game, and if a simple menu can prevent mass quantities of future Q_Q GM calls on so-and-so who cheated you out on a deal or making more threads on forums about so-and-so being a scumbag for whatever reason, the better.
Less drama was a good thing last time I checked.