I can name a few reasons why we should not move to Twig:
- Twig is view-driven. XTemplate is controller-driven. Twig blocks are absolutely different things rather than XTemplate blocks. Twig blocks are hierarchic structure elements. XTemplate blocks are parsing logic elements as well, still driven by controller - which is pretty unique to XTemplate, despite the fact that it is still push-based like most MVC template engines. This means that you cannot replace XTemplate with Twig without rewriting the controller logic completely.
- XTemplate2 was built in KISS spirit, just less than 500 lines of code which do the job. But a hundred classes in 250kB of code means no simplicity of this kind.
- Do we really need that complexity in TPL files?
For me point 1 is the showstopper, the rest 2 are more or less acceptable in some circumstances. In addition, compiled templates don't always mean speed, in case speed claims make you choose Twig.
