It has been pointed out a few times there are major differences between the 2 projects.
1) In simple terms, the 227 patch/update is a re-build of the Unreal engine, and the SDK is a suite of tools you can add to UEd and UT.
2) The 227 patch is "finished" and the SDK is still beta.
Both require a user to update, and is no different than having to update an old UT to GOTY standard with the Bonuspacks etc.
As long as any map using either system, clearly states "you need this" I have never had an issue (unless the required file is no longer available)
Both require maps to be made to see, what all the fuss is about (Though the old pre-SDK mutator can give you a taste of instant shiny).
http://www.moddb.com/mods/utcommunitysd ... ip-versionI am aware a few others have got lost with installing the SDK, though usually because they did not read the file "Setup.pdf"
The files all go into the respective UT folders and not in it's own folder, then add/edit the 6 or 7 ini entries.
Now when you open UEd, you will have a whole lot of new toys to play with

There are some similarities in the things you can achieve with either, but the UT market is bigger, so it depends on your objective.
Unreal is after-all a lonely Single Player experience.
Whereas UT is all about meeting new friends... and killing them as humiliatingly as possible (that's where Food Fight comes in).

I don't know what you mean by KVARTAL being over-ambitious. You may think my personal version is way over the top then
I have vehicles so the long walks around the block are a breeze, and should you go into the woodland the rock-titans will get you.
and I always play it with the Zombies v5 mutator (same as Creavions jungle maps, though the zombies make you more paranoid in the jungle!).
Actualy playing DM-KVARTAL as a "DarkMatch" with flash-lights and zombies would be awesome!