theturninggate: this fact is known in the development team and we are thinking about a better implementation.
For the rest:
PEL requires PHP5, like you stated, and that it is the main reason why we don't use it. PHP Exif support is nice, but this is a module that needs to be compiled in the PHP setup by your hoster.
In fact, we're thinking about a way to fix this in version 2.0. With all the changes we have done lately we decided not to change the exif routine. This will give to many compatibility issues, so we decided to take it slowly.
dakwegmo: I take it you're a Nikon shooter? Perhaps I can include the makernote again, but there were issues saving it to the database. These issues might have been resolved but I need photos for testing.