I typically prefer a Zen-based theme. I have gone through the memory optimization steps posted on this site (actually, I've gone through them several times recently thanks to the multitude of updates .... )

I have deleted all of the carrier-specific themes. Which of the RIM/BB themes can also be safely moved to my "removed modules" folder?

Kris, in the removed modules folder, as in never loaded to the BB? All of them if you need that space on the PC.

net_rim_theme_bbdimension_zen_320x240_b.cod

That is the 1 that 3rd party themes are usually dependent on. (for ZEN themes)

This one should NOT be removed.

I think you can safely remove the icon cod file with no ill effect (but it's only like 14 KB or so, so the memory gain will be negligible).

You biggest memory gains are from removing language files, voice activated dialing files, and the preloaded media.

Excellent! That's what I was hoping. I run a fairly large 3rd party program for work. Any spare memory byte helps!

I agree on the Zen Dimension file. When I upgraded to 4.5, I wanted the L-Theme and I thought the Zen was only needed for "Zen" themes, so I didn't load it. Either it is needed for more than just that, or it is also needed for the L-Theme because it would not load my theme until I loaded the file.

If you remove Dimension themes, then you will be unable to install 3rd party themes of that style. ie if you remove Dimension Today, no 3rd party Today themes will work.
This really should be clearer in those memory guides.

Yea, was about to say what Storm said, if you remove whatever BB Dimension theme you won't be able to use any theme of that type for any custom themes. Found out that on the hard way lol

I removed the BB Dimension Today theme and the BB Dimension Today Plus still works for me. I was actually surprised that it worked...

I kind of read between the lines and thought you had to keep the stock theme that forms the basis for your chosen style (if that makes any sense at all ..... its late and its Monday).

That's because that isn't a 3rd party theme, it's a RIM theme which are applications and include all the requirements.

No wonder why Thanks Perfect.

I tried the Dimension L-Theme without the Zen-theme (I don't know if L-theme IS a Zen theme, but I assumed it wasn't) and it didn't work. So I guess you can just keep one of the Today themes, but you have to keep the Zen theme if you want the L-theme, or a 3rd party Zen theme.