We are currently re-platforming from an old e-seller pro eCommerce website to Magento. our domain has been registered for over 15 years and Google has indexed the existing website, we even show on first age for some low traffic keywords.
Our primary reason for re-platforming is the SEO capability of existing website is really low and we want to think we can get more traffic with a Magento platform.
My concern here is will our site dip in rank drastically and need a humongous effort to get back up into its usual rankings?
Our rankings are not impressive but I'd prefer not to fall further in Google rankings.