I don't want to sound like I'm advertising or something, but it does sound like you'd benefit from reading the FAQ I wrote here:
http://androidforums.com/galaxy-s2-boost-mobile-all-things-root/698058-faq-boost-galaxy-s2-faq.html
Regardless of that, I would say you have more or less answered your own question when it comes to if you should root. If you have no reason to, why root? I know for me personally I loved this phone as stock too, and had a similar outlook. I am definitely the type person who can't just leave good enough alone though so I ended up modding and rooting.
So far, I have found that CM10.2 is the best rom I've used overall. The battery life could be better (and there's still a possibility that's just my battery at fault), but overall, the ROM is extremely stable. If you think your phone runs well on stock, you'll probably be amazed at how well it runs on a custom ROM. I was impressed with the speed boosts I got, when I thought the phone was plenty fast to begin with. I also have found that I quite like Jellybean. Installing the nitro injected tweak has meant my 3g speeds are sometimes as fast as 2mbps, where before it averaged well under 1mbps.
I think ROMs are a matter of taste though. I like something that mimics how a stock ROM might look and act. I don't really want a lot of fanciness, and don't like too much themeing. These reasons may sound silly to others, but here's my list of reasons why I prefer to use custom firmware:
- Toggles in the notification menu
- The ability to hold the home key on the lock screen to toggle the flashlight (or, in roms that don't support that, the ability to access it right through the toggles)
- Ability to place applications in the lock screen, so that you can unlock the phone and go directly to the application (this is especially useful for the camera, the phone, and calculator)
- Integrated tethering/hotspot capabilities that can be toggled using toggles or even added to profiles
- Better battery life indicator that doesn't take up much screen space
- The ability to run root-only apps, such as droidwall, titanium backup, adaway, market unlocker, sixaxis controller (haven't used this one yet, but can't wait, i love emulators), root file explorers (i prefer root browser), and others i'm sure i've skipped
- ability to overclock and/or enable USB host mode (this doesn't exist in JB yet for our phones, but future development may allow for it if we ever get source)
- tweaks/mods such as the ability to add beats audio sound libs for better sound
Just my opinion... to each his own of course
