Currently i'm using latest stable version of PHP, webmastering a online shop with Doctype XHTML.
Most of our customers use "old" browsers, 25% use IE8, 10% use IE7, 3% IE6 (however, IE6 never purchase, the shop looks weird in IE6 because of PNG usage - we are not willing to strongly support IE6 anymore). Rest: FF, Chrome, div.
Currently, I pretty much like the way, tidy cleans up the page. It provides better UTF8-Support, adds ommitted tags and - most important to me - always provides a w3-valid website (so I can put the badge on it).
What I don't like is the missing development of the extension. I feel, it is quite impossible to make the page HTML5-ready. Why would I want to use HTML5? Mainly because auf schema.org. Our page added some product Info in microformats, however they are not supported very well. Microdata would be better.
So, is it still adviseable to use html tidy just to get a "cleaner" source code, or should I provide HTML5-Support. (I would still have to use tidy for user-input like the description of our products).
Moreover, will "older" browsers have problems with HTML5 or will they just ignore it?
And last but not least: Will avoiding tidy speed up my page?