Custom Build or Thesis/Genesis

What your project/website is for might help you determine that.
You said your working with a "designer"...... are you sure he's an expert at development?
A designer and a developer are not the same thing, or the same skill-sets, although there are some who can do both.

Faster? not likely, the Thesis/Genesis framework is already in place.

Not break during updates? hmmm.... that's a pretty strong guarantee.
It would require consistent updating. Many WP updates are small, but there are also many large improvements that require updating the theme's core. (Thesis/Genesis do this consistently).

I think your last statement is likely a concern worth thinking about.
It won't be tough to find someone to work on it, but you will have to pay someone (or the present person) to update any issues that may arise during a WP update.
Most developers with a custom one-off theme, will not continue to update your theme for free. (Thesis/Genesis updates are part of your purchase).

Bottom line, what "He wants" doesn't matter too much, what you want and the best way to accomplish it is really what matters.
It sounds like (I could be wrong...) your being pushed towards a custom setup (which =more $).

Don't get me wrong, I'm a huge fan of "custom", but the fact that he's pushing you towards custom AND wants to use Dreamweaver??
That kind of makes me wonder how professional he really is........
(yes, Dreamweaver is ok, but not the optimal tool that the majority of professionals use).

Thanks DV.....

Just for clarification, he is a developer. He mentions converting HTML files(?)

I was going to use Genesis but the Thesis 2.0 framework seems like a viable option as well. I think he may be concentrating on the 'looks' which is a short term win.....but when you play the long game, it looks like a full custom theme may be a bit dangerous being that I can't diag and fix problems that arise.

If you are talking about a custom site as opposed to a site using one of the premium themes you mentioned, it could be a lot faster than WordPress, I think you already know the only thing that could go wrong with that idea.

I prefer to work off of the genesis theme. But, it comes down to personal preference in my opinion.

We all know that Wordpress, if not optimized, is not really fast regarding loading times.

Every plugin loads its own CSS/JS files (and ofcourse in the head section, where JS does NOT belong).

When I hear someone calling himself "designer" or "dreamweaver" I have to laugh...

Custom does not mean Thesis/Genesis to me... if a dev knows what he is doing he could just use a solid CSS framework (I prefer ZURB Foundation).

If someone is selling "premium" themes, or his own site has a premium theme installed, I am asking myself if that guy knows HTML/CSS at all...

Oh, using a theme framework like Thesis does NOT mean it is not a custom built website!

Customizing a theme that's already done is wasting a lot of time...

Using Genesis Framework and build a custom child theme from scratch. That's truly custom because your designer/developer design from scratch but based on the functions of a framework.

If he/she is using child themes whose packed with the framework and do customization, it's not a true custom one because it based not only on the framework functions but also the markup codes.

If yours could codes from scratch without using any framework and is using the standard coding of WordPress as well as well commented code structures, there is no point to worry if another qualify developer comes to maintain in the future.

In contrast, seems that your designer/developer aren't qualify enough because of his/her ignorance of the respond. Custom theme with or without framework, there are slightly different in speed if it's well coded and well optimized.

He/she would know that the speed would be solved with many things in WordPress such as minimal plugins used, exclude unused codes, optimize images, use sprite, using cache, and many more.

It seems he/she couldn't implement the theme development with the framework, that's why he/she reply with such a solution.

I can design Genesis and Thesis child themes. Contact me

Loudesigns.net