What do I get if I install a custom ROM instead of installing new launcher, new phone app, ...? I have been thinking about installing a new ROM, like CyanogenMod (most probably), but thought it would be a mess to return to stock ROM if I messed it up, plus, last time I checked, not all features are guaranteed to work (camera, tethering, ...).

Now, my question is not about how to backup the old ROM, because I found another solution: as my phone is rooted, why not remove the stock launcher, the stock music app, stock browser, all the Samsung Software Update and Holy Quran and Samsung Apps and Swype and all the apps Samsung forces me to use? These are easy to back up (in case), and I can replace them with a browser of my choice, ADW Launcher (CyanogenMod's one), music player of my choice, keyboard of my choice, etc.

So what does a custom ROM offer more than just custom launchers and widgets and looks? Or is my option "utopia"?

Note: I'm not sure if that matters, but I'm on a Samsung Galaxy Fit GT-S5670, Rooted Android Froyo 2.2.1

Another Note: I read this question and its answer, but the answer there only states things that could be done with a home replacement app...

UPDATE It seems nothing can't be done with apps. It's just easier and faster and more stable to use a custom ROM, that is if the ROM for your device is stable enough.
Two major cons to simply using a different launcher Vs. a whole new ROM:


Custom ROMs often offer a later version of Android than is available for your device from a manufacturer or carrier.  No amount of launchers will give you the newer functionality of latest OS versions.
Very often removing manufacturer/carrier "bloat" is not as easy as deleting some APKs from /system/app directory.  In cases of custom UIs such as Samsung's TouchWiz, or Motorola's BLUR, or HTC's Sense, many of their apps which replace stock core functions (e.g. Phone/Dialer, Contacts, etc.) are interwoven with the system and each other in such a way that simply removing them may cause crashes or other system instabilities.  Installing 3rd-party replacements does not resolve anything, since these apps are always running in the background, using up valuable resources.