I'm NOT working with:
joomla, drupal, wordpress, modX
I am expert in:
Magento and highly loaded web-applications.
For last five years I'm investigating Magento from inside and have pretty good results in making it work as you need. Successfully passed both available certifications in Magento (http://www.magentocommerce.com/certification/directory/dev/340/)
If you need to customize you store or have your magento unexpected behaving itself, than you are definitely looking at the right profile. Feel free to discuss your issues and a