Use preinstalled service feature or not?

This is really too vague. There is no best practices, there is business requirements and how to satisfy them. 

Sorry for that, I read that using preinstalled service required modifications on the DC after which admin perms are not required for the QMM account. Is there any other benefit to use this service?

The benefits are you can migrate passwords and sidhistory with the need for an account with membership to the builtin\administators group. 

I think most of your questions can be better addressed by our Professional Services team. From a previous message I understand you were already contacted - still, if you need further assistance, email me at my name dot my lastname at quest dot com and I'll put you in touch with someone who can help.

Hi Alex, I've send you an email. Thanks for your support!

Jeff, please read the quote below which is stated in the tech doc about the preinstalled service feature; my understanding is that using a sync account w/o the need to be in the administrator group when this service is used. Looking forward to your feedback, thanks again for your support!

"The preinstalled service feature allows you to use Active Directory synchronization accounts that are domain members not included in Administrators group to migrate passwords and/or SID History"

Jeff, please read the quote below which is stated in the tech doc about the preinstalled service feature; my understanding is that using a sync account w/o the need to be in the administrator group when this service is used. Looking forward to your feedback, thanks again for your support!

"The preinstalled service feature allows you to use Active Directory synchronization accounts that are domain members not included in Administrators group to migrate passwords and/or SID History"

Jeff Shahan said:

The benefits are you can migrate passwords and sidhistory with the need for an account with membership to the builtin\administators group.

e atar said:

"The preinstalled service feature allows you to use Active Directory synchronization accounts that are domain members not included in Administrators group to migrate passwords and/or SID History"

The both state the same fact. Was there a question? 

The question was actually in the 1st paragraph, you only quoted the 2nd paragraph of my message. Anyhow, in your statement you said "with the need" but should be "without the need" which make sense . 

Jeff Shahan said:

The benefits are you can migrate passwords and sidhistory with the need for an account with membership to the builtin\administators group. 

It's clear now, thanks a lot four your help!

Yeah. At times you become blind to the words actually written verses what you think you wrote. Autocorrect does not help either. Flad

you understood the point I was trying to make. 

Absolutely!