My Dinan springs are being installed as we speak. Dropped the car off today and should pickup tomorrow afternoon. Will let you know what I think and post some pics then!
However in my opinion you can go either way with Dinan or H&R or Eibachs or RD and there are folks on the forum who have done each of them and have pics and opinions accordingly. Pros and cons to all but for me it basically came down to the fact that this is my daily driver and the streets are pretty bad here sometimes/mosttimes and that I don't track much at all but want to still be able to do so too. But the overriding pro for me was the warranty coverage and Dinan's research and history of R&D before he releases products. Yeah they cost a bit more but I just felt that Dinan does ONE thing and that's BMW's and does it well an only releases upgrades that would meet factory tolerances in the likes of Ruf or Alpina so why not spend the extra $$$ (only a few hundred and less than a grand) on a good quality part?
Also I got an additional discount from my install shop on the Dinan parts and labor/install to go with the 15% Dinan is offering now so that just sweetened the deal to get off the fence and do it now!
'12 F10 550i (Dinan Stage 5, LSD, Intercoolers, CF Intake/Brace, Shockware, Springs, Eisenmann Race Exhaust, CF rear difuser, Giovanni "Lindo" Graphite 20" wheels)
'10 e71 X6 35iDrive SAV (Space Gray) - Gone
'06 e85 Z4 M Roadster (Black Metallic) -Gone
'08 e92 M3 coupe (Sparkling Graphite) -Gone