It’s hard to say which platforms suit your needs without knowing what they are. Do you have special requirements that are unusual in the world of e-commerce? Having said that, a decent e-commerce infrastructure will allow you to tailor key features to fit your needs in a reliable manner.
As @usoban suggests, Magento does not require Symfony, but it is built using the Zend Framework . Therefore, if you are familiar with Zend templates, you adapt to Magento faster.
Magento has a wide range of out-of-box features and is certainly capable of scaling large transaction volumes and visitors .
This requires major optimization of the hardware and resources in this high-quality configuration, but there is a wealth of knowledge on how to achieve this both on the Magento website and elsewhere on the Internet. The Enterprise Edition is also designed to improve performance (including full page caching), as well as features / functionality important for administering serious e-commerce (merging and creating content, detailed permissions, etc.).
You will hear many complaints about the Magento learning curve, and they are mostly justified, especially if you come from the traditional background of the PHP encoder. However, if you spend time working through tutorials and find out that complexity is related to the power and flexibility of the system, you will probably find it appropriate. In addition, we, StackOverflow, believe that you will get much better support here than on the Magento forums :) There, as a rule, there are some dubious tips, at least here you can see what peers think about the answers :)
Hope all this helps!
Jd