Hi,
I am considering offering a commercial, subscription web service based on Joomla technology, third party extensions (both GPL and commercial) and custom templates, modules, and components. I am seeking opinions from those with similar operations or credible insight to the legal implications of what I am pursuing.
Before posting here I conducted a fair amount of research into the GNU GPL and OSM licensing details and searched and read through many forum posts until the relevance fell under 20% and older than a year in age.
My belief, based on my understanding and interpretation of this research, is I am clear legally under the following scenario and conditions:
1) Seek professional legal advice to be certain!

2) Service offering is commercial (customers pay a fee) web based application including:
* web hosting (24/7 Internet access and availability, domain name registration services, technical customer support, etc.)
* access and use of specialized application functions
* initial client setup (user profiles and default data loading) and customization of application interface
* additional fee based services such as customizations to non-GPL code, new custom code and functions, training, ongoing site maintenance and updates.
3) No code obtained under GNU GPL and OSM will be altered and will be referenced via the website hosting the subscribed application service.
My rational goes as follows:
1) No open source code is being modified, sold, or distributed as all executes, operates, and resides on the hosted site. Even if open source components were deemed modified, license is not violated as no code is being distributed.
2) Subscription fee is derived for hosting, application services, and support services.
3) All customizations are done via "ground-up" modules and components not linked into open source components but invoked via published interfaces such as API, functions calls, forks, and EXEC. **
4) Identification, copy write, and reference to utilized open source functions is published in hosted application.
5) Ability to clearly identify distinct open source components and functions, custom functions, web hosting, and professional services.
6) Existence of GPL and custom code, modules, and programs on common server would be characterized as "mere aggregation" rather than modified code.

All customized, non GPL code would be copywrited by author and not released under GPL.
9) Open source components would retain original GPL/OSM license text in version residing on hosting server.
** Not quite sure about "dynamically linked" clause for plugin as I am not technically sure how Joomla extensions are implemented but based on the existence and legal commercial third party Joomla component market I am assuming this is acceptable)
Thanks for your input.