I really really don't want to start a who's-better-thread, but i just read about Simplepie's part in the development of Lilina and want to know some things: I'm running a search engine that's indexing blogs. Currently there are 6000 blogs, indexed every 24-48hrs via a massivly pimped version of simplepie 1.1.1. (1.1.2. is buggy). Yeah, i know this is HEAVY, but there's no other way to do this ;)
So, which are the advantages/disadvantages of lilina ? Is is faster ? Better recognition of special characters etc ? I'm really excited bout testing lilina in my environment, but this will need a lot of work.
In my opinion SimplePie has just one major problem: The PHP-memory-cleaning-bug [this is not simplepie's fault] ! this makes tiny scripts use MBs of RAM, in my case it's more than 1 Gigabyte [of RAM]. How does Lilina handle memory ? Is there a cleaning function ?
The main difference between Lilina and SimplePie is the fact that SimplePie is a development tool, while Lilina is geared towards end users. Attempting to compare Lilina and SimplePie is like attempting to compare WordPress and CakePHP/CodeIgniter/Kohana/insert-other-framework-here.
Personally, I believe you're best sticking with SimplePie. In your case, you're using it as a developer and so anything that you can make will be faster, lighter and more geared to your purposes, simply because you know exactly what you want and don't have to implement anything else. Lilina uses the SimplePie library and therefore, can't be faster.
The PHP memory bug is an unfortunate one, however I believe (I may be incorrect on this) that Lilina avoids it completely, because the SimplePie object is available at all times, until Lilina itself exits. We only have one master SimplePie object (although, internally, SimplePie creates a new one for each feed) and this is needed for template functions, so we don't unset or destroy it manually at all.
I'm very conscious about Lilina's memory usage and load times, so I'm constantly running it through XDebug and profiling the code to try and squeeze the best performance possible out of both SimplePie and Lilina.
Full disclosure: I'm both the lead developer of Lilina and also a co-developer of SimplePie.