What is to be understood by "Fluid powered TYPO3" (as stated by http://fedext.net/) and what are its benefits for the integration?
Are there other modern templating approaches for TYPO3 6.x that would be best practice to switch to now?
I don't understand the different systems that are around at the moment and I need some clarification.
The background of the question, what I am looking for:
And what about https://github.com/Ecodev/bootstrap_package ? Is it recommendable?
Fluid offers a much cleaner approach of dividing template logic from display logic and controller logic. Your result will be structured much better when using the possibilities fluid and the mentioned extensions like vhs provide (like layouts and partials).
The usage is actually very simple but can still be combined with the oldschool marker approach (you can do things like <f:cObject typoscriptObjectPath="lib.marks.MAIN-MENU"/>). If you need more flexibility in the backend like in TV, you (of course) have to code some things yourself.
The easiest way is to use an extension which is created by modelling it in the backend to fit your custom needs, but you can also adjust the rendering of pages and/or default content elements by using typoscript and the fields given (like pages.layout, header_layout, section_frame and so on).
So you always have the choice between detailed inputs (extbase extension objects) and using the TYPO3 default things like page properties and RTE config in combination with some typoscript magic (css_styled_content).
So as a conclusion I strongly recommend using fluid templates and additional extensions like vhs as they provide a lot of (additional) power and reusable templates while still let you use markers if you want to. Personally, I also prefer to enhance or limit the RTE in the backend in favor of writing too much special code for an FCE-like result.
BTW: There are very good autocomplete features by using the DTDs/XSDs from fedext.net in your IDE which made my template programming much faster (like 25%).