I just switched to Platinum form standard and have been sorely disappointed.
I'm having to spend way to much time debugging page source code and customizing css to get things to work and look right on my site. Can't get anything to look right in Internet Explorer. Everything expands to display full width which looks terrible on large format screens and IE doesn't respond to custom css..
I'm getting lots of complaints from site visitors and lead sign up is way down since switching.
Support has been slow to respond to issues. They're probably overwhelmed.
I recommend you wait a while before switching. Platinum is not ready for prime time. The added expense does not justify the few "additional features" and themes. Especially when they don't work out of the box.
If you are very good with css and html and have time to develop your site then you might enjoy Platinum.