Kill team is still 40k. Just scaled down. Anything to add diversity is nice, and it'd be a great way to play quick games, or get started with a new faction. I think it'd be fun to participate in a kill team organized play event.
I still find 40k to be a great game to play. Especially now with all the options there are in building armies. Sure, people find ways to abuse it, but it's the same with any game. have a blast getting in games, and I look forward to events I have coming up.
Kill team has a low investment (200pts of models can be as cheap as a box of tactical marines), so it's not hard to get a force built up for it. No reason not to try it out, and the rules are available for $10 (Canadian) on the Black Library site.
Would I say that it's better then playing a normal 1500pt of 40k? No, just different. Same as playing highlander, or 40k Classic, or ITC. All different ways to play with their own pros and cons.
My own LGS has been playing 400pt games recently as part of a getting started league, and I'm really enjoy it. My poor Tempests Scions enjoy getting the snot beat out of them, but I can play two games in an hour. The biggest issue I find with playing small sized games, is that I can't stop itching to expand to larger games.
Irisado, if you like the small game format, you should also look into the Generals Handbook for Age of Sigmar. They have rules in there for warbands and I think it'd be right up your alley. I think that you would really enjoy Age of Sigmar, as it's the streamlined flexible game I think you'd like 40k to be.