I wanted an indoor solution to our "no external antenna" HOA-NAZI regime. Even with crappy band conditions if I hear them, they usually hear me. I've used this on 10,11, 20, and 40 meters using 4-20 watts (4w when using my FT-817 and 15/20 when using my TS-2000).
I don't have a dipole or other base antenna to compare it with and only know what I've read online when it comes to that type of A/B comparison. I did do a "2nd floor-indoor / outside-of-garage" test and didn't notice a big difference.
As well, I compared the MLA vs. my mobile antenna and it was about 1 or 2 S-Units less with the MLA. As you've probably read, if you move around a band much, prepare for a lot of turning the V Cap. This has never really been a sore point with me. Higher up in frequency (10/11m) it's a larger bandwidth so usually I don't have to mess with the v cap much at all. Would I go with an MLA again? Given my circumstances - Yep.
The mantra I try to follow is: "The best antenna is the one you have to use" (or something like that).