If you're on your own and eventually you'll shut everything down or pass it along to your children then keep on doing what you're comfortable with. But, if you think some day you'll want to bring in investors or sell your business then customized books just won't cut it.
Your statement of accounts will be unfamiliar, your financial entries will be in review, your profitability will be questioned and there will be a great deal of debate on the finances of your company. Its going to be a tough courtship and it will make it much more difficult to get the deal done.
So save yourself the pain and audit yourself. Hire an independent auditing company to audit your books and put their stamp of approval on everything. If you have three years of audited financials in a row you'll be in good shape. Five years is ideal. If you bring in the auditors in off season they will cut you a good discount. The first year of auditing will be a pain. There will be many questions and it will eat up a lot of time. The pain is worth it though. You'll have a good understanding of your financial position. Auditors will typically have some recommendations for improvements. Subsequent years will get easier and use up less time.
In the end when you hand over years of audits the conversation will be very different and you'll get down to brass tacks - what your business is worth.