TNEW Guest Checkout Experience

We are investigating whether to allow Guest Checkout when we Go Live with TNEW. 

One of our main concerns is the data clean up with Guest Checkout. 

I am looking to get feedback from other TNEW users on what is the affect of the Guest Checkout on

• Duplicates
• Cleanliness
• If you don't use Guest checkout, do you get complaints from patrons?
• If you don't use Guest checkout, do you have a higher rate of cart abandonment on the check out page?

Thanks for any feedback.