I have a front loader and it felts just fine. However, it doesn't felt as fast as a top loader. I have seen videos of felting tutorials and after 5 minutes or so in a top loader there is remarkable felting progress. I don't think 5 minutes in a front loader would get such results.
So, I have resigned myself to the fact that felting in my machine takes a full cycle to felt (just make sure you don't spin -- you can get creases that won't come out. Ever. Take my word for it -- I have a cute little creased purse to prove it.)
I follow pretty much all the regular directions for felting -- I may check mid-cycle to see if my felting is finished, even though I know that most stuff needs a full cycle and sometimes more than one cycle to get it to where I like it depending on the brand of wool I have used.
You will need to experiment with your own machine until you discover what works for you. I haven't felted anything other than bags yet so I don't know what would happen with something where size matters like a hat or a pair of clogs. I think I would just check my progress more often than I do with the bags I have felted. I haven't yet gotten anything that came out too small.
Hope this helps!