question to End-Users of PHP_CompatInfo

For those who have already have a look on new API 1.9.0, you've certainly find a basic very little Extension Support List. Paradoxically I don't wanted to have a break on backward compatibility with previous versions (1.8.1 or less), but you need PHP 5 to build your own Extension Support List (with pciconf CLI script). BTW, that is why I've asked my question about package xml v2 ;-) This case may be perharps consider as a problem by the PEAR QA team ! I don't know their opinion. So my question is to embedded in default package almost all main extension that 90% of end-users used. This will limit disappointment of pure PHP 4 users ! What do you consider as to be a mandatory extension ?