Upgrading to PHP 5.3. Can I stay with MODX .9.6.3 or upgrade first?

I have a .9.6.3 install on a server that I want to upgrade to PHP 5.3. The current install is essentially unsupported because our one MODX developer left so I'm wondering if, as a rookie, I would I be better off upgrading PHP and tweaking the .9.6.3 config like mentioned here: https://forums.modx.com/index.php?action=printpage%3Btopic=37293.0

or if I could smoothly upgrade to MODX 1.0 (or higher) and then do the PHP upgrade. The site only runs a Doc Manager and QuickEdit modules. It does include several Snippets though.

I appreciate any advice. If seeing the site helps, it is www.embassyseries.org
Cheers

I would recommend upgrading your MODx first. The modules and plugins will be no problem; you can upgrade them at the same time.

The snippets may be a problem, as some of the older snippets, particularly the AjaxSearch snippet, have changed their properties and the snippet tags need to be adjusted to use the new properties.