Financial stress while doing startups is very distracting and possibly deadly to the new company. Plus your income can help fund expected and unexpected expenditures.
I've done 8 startups, only one from my savings. I'm on #8 right now with a job and slowly building it on the side. It's 12-16 hour days sometimes but I have health insurance covered, paid time off/holidays, and significantly more revenue than I need with dual incomes.
I'm leaving once there's enough capital in the company to cover myself and my partner's payments for 1 year with no income and our first 5 clients.
If you feel you're not giving your customers the service they need, you can setup a small coloc office and hire a 15-20/hr employee to man the phones give customer support.
Good luck. I worked on AR products in Oil & Gas, some of the worst crap I've ever seen in my life. A good workflow will make your users love your product, so eat your own dogfood :-)