I have three MC-0.5's (only two installed) and a pair of HFC's Magnetic RCA adapters for my TT tone arm cable. I have to agree with @ozzy and @jmcgrogan2. I like the effect the MC-0.5's have on the sound and sound stage. Especially on the tonearm cable.
I recently added the Magnetic RCA adapters, so I'm currently evaluating their effect before introducing the third MC-0.5 into the mix. According to Casey at HFC, the MC-0.5 takes aprox. 150-200 hrs. to "settle down." But the more you have installed or coupled with other HFC products, the shorter the time it takes for them to break-in.
The RCA adapters with consistent use take a bit longer (guideline 300-400 hrs.)