And you can make the choice a UserOption.
You can make the Postbit selectable using this method:
How To Make the Postbit a User Option
http://www.vbulletin.com/forum/showthread.php?t=101577
And there is a plug-in available here:
Easy Postbit Switcher
https://vborg.vbsupport.ru/showthread.php?t=91620
If you use this second option, you only need one style and an "option" Radio Button choice is given to your users in the UserCP to select one or the other.
Regards,