Yes you can upgrade to 2.9 just make sure that the upgrade licence it´s not expiredmine mikrotik this in version 2.8.10 I can low Packages 2.9.17 and install?
Just a question: What's wrong with routeros-x86 for updating from 2.8 or older to 2.9? Strange effects like spontaneous reboots, missing features or just "you can become unexpected problems with feature x"?do not forget information about upgrading from 2.8 to 2.9 in download site.