I’ve been using Genesis for about 3 years in various projects. I thought I would be able to create more complex themes by using Genesis, and I can’t. I thought I would consolidate a lot of plugins into the core functions of a well programmed theme/framework. Originally I could, but now I hardly need to depend on Genesis for anything.
If you are going to run a large site, it would be impossible for you to find someone to write code as clean and efficient as Genesis. I had a friend opt for a non-genesis theme – a really vanilla theme, mind you – and he gets more out of memory errors in his log than all my other sites combined. It’s a big deal. Your site will simply not work properly and you won’t be sure why.
It’s like buying a car: do you buy what you KNOW is reliable and will last 200,000 miles if you need it to, or do you take a chance on what feels good and see how it goes. With a car, I didn’t care so much when it was driving to an office every day, but I cared a lot when it was driving to a client every day. My website is like driving to 1,000 clients every day.
I thought the variety of themes and the flexibility would expand as time went on, and I have been disappointed there. I wrote the owner a letter and he wanted to talk to me about it. (I’m nobody special.) He, on the other hand, is insanely busy. That was awesome. Seriously. (We’ve yet to talk – my fault.) Originally I bought the framework because it bridged gaping holes in WordPress of yesteryear (2.8): breadcrumbs, SEO, menus, buddypress themability (add-on). I don’t really have those concerns any more.
As for your questions, I think they got covered above. I’d advise you to try to use something that’s being used by the theme, or another theme in StudioPress for the support you can get for it. I could be mistaken, but I’ve played with many of the themes by now, and you don’t have to do anything their way.
In the end, the people monitoring the forums are great – very helpful and nice. But they’re expecting you to be able to operate at a certain level, so ask for the help you need and don’t be surprised if you sometimes get an answer that’s over your head. I don’t think anyone will tell you that you shouldn’t be there if you don’t know how to do something. In the end, the subscription is worth it just for the support you’ll get in StudioPress forums. So much help, so quickly answered. Such a knowledge base in questions already asked.
I’d also suggest you look at the list of plugins that do only work with Genesis installed, for the features offered there may give you functionality that really enhances your experience.
If you want to talk more with me about it, just send me a message. I have a guy who does design for Genesis child themes, too.