Data security is probably the least of your worries when it comes to Intuit.  Unless your practice devotes the same level of technical and financial resources as Intuit to protecting the business franchise, Intuit's IT system should be more secure than those of most small to mid-size practitioners', IMHO.  Don't forget that Intuit is also subject to IRS oversight.

https://proconnect.intuit.com/tax-online/faqs/