It would certainly be possible to get extremely close to that layout – yes. Mainly a matter of re-ordering the columns and moving a few things around…
responsive basically means the theme adjusts its display automatically for different screen sizes.. ie desktop vs tablet vs phone, etc… it kind of reconfigures itself to look proper based on the screen size available…
If a custom theme is created for me, what happens as new versions of SP are released? Do the themes still work completely, or need to be revised?
I think I’d like a bit of a customization, but I’ve been working with SP for less than a week, so I’m not sure exactly what I’d want yet. But hopefully I will be able to spec it out soon enough.
The Simple:Press team works very hard at keeping older themes compatible with Simple:Press updates. In most cases when you see a theme update it is because of changes to WordPress (when they update) or to add in a theme or plugin feature not previously available. There is not much anyone can do if WordPress changes something and the theme has to be updated because of that but typically there are not a lot of changes between minor versions. Like 3.5.1 to 3.5.3. There can be quite a few in larger updates like 3.5.1 to 3.6.0. But even in those cases there usually if very little SP theme changes needed.
The key is starting with the latest theme files. I don’t know if everyone does or if they have their own shell but all mine are derived from the latest. 
Then Simple:Press maintains a list of all theme changes on every update. For example here on the last one.
http://codex.simple-press.com/codex/installation/changes/theme-and-templates-5-2-3/
That way you can see what changes were made and if they are something you want to add.
as Brandon says, we try to never break backwards compatibility… Its of utmost importance… That said, every once in a while, we run across something that has to get changed but those are extremely rare…
99% of the time your theme will keep on working as is…
Now when we add new capability, that is a different story… If there is new functionality, you may not be able to get at the capability without modding your theme, but of course, that is no different than wp themes and would be expected… but the old theme will keep working as it was…
Re: “Simple:Press has several themes and overlays available right out of the box”.
Having downloaded and installed the 5.3 version, there appears to be only the default theme. Where do I find the “several themes” you refer to?
on our download page… see nav menu at top of this site…
and btw, overalys are part of the theme… so the default theme has 12-15 overlays which are different color variations…
then there are another 3 or 4 themes available on the download page… and a mobile theme is coming soon…
By any chance do you have a version of the theme you use here in this forum?
The colors aren’t my concern as much as the layout. The default layout, in my opinion, is just too cluttered with buttons, links, and dropdowns at the top. Since I’m still a new user, I can say I’m overwhelmed by all the options. The theme here has none of that….just a search bar at the top….AWESOME. 
Ummm… a little confused as there isn’t really much difference between what we are using here and the default. Can you give me a link to your forum page so I can take a look?
Beta forum (colors will not be final) http://www.werejustparents.com/forum/
The header has a lot going on….here the header shows:
Search Bar
New/Recent Updated
Profile
Breadcrumb
We can start going through the theme and making changes, I’m used to that with what I used to use for everything (phpBB). Just wanted to make sure I’m not overlooking any themes before I start going that route.
Thanks
But I don’t see the difference between this one here and yours. Well – apart from the obvious one of colours of course. I must be missing something but it looks more or less the same. Can you be more specific about the differences?
the breadcrumbs are different, but we have posted in a couple different topics how to achieve that look…
other than that, I am confused like Andy…
I wanted to take this opportunity to highly recommend the custom theme service they offer. By utilizing this service the Simple:Press guys were able to create a theme unique to my site and addresses all the objectives I had which included:
The pricing was very reasonable and the turn around time was excellent!
Thanks Again!
Jody
Gosh – thank you Jody. This really is very much appreciated.
We actually enjoyed your custom work – got the chance to add a couple of new items…