Mine did the same thing, I bought the Lyndall Z+ and put them on the rear only. I noticed the fronts stopped a lot better. I figured they would break in and get better, they didn't. So I bought some for the front to even up the stopping feel. Then after 600 miles, I rode my friends 08 with Brembos (same as the SERK) and I thought damn this thing stops a lot better than mine with the Lyndall pads. So I put the OEM back on, and it does stop a lot better.
I'm wondering if I should try the gold plus pads from Lyndall. The Brembo brakes stop a lot better than the normal Harley calipers and when you put the Z plus pads on, the Brembo's feel like normal Harley (non Brembo).
I have a little bit of noise with the stock pads, but I haven't ridden it that much, so I might have to give the gold plus pads a try. If you did them all at once, or didn't switch to another Brembo equipped bike, you might not notice. But when I put them on the back only, every time I grabbed the front I couldn't believe the difference.
That is my experience with the Lyndall pads on my 08 SERK.