It took alot of work and fanagling to get everything in properly.
This person must be pretty unfamiliar with the gun and you probably would have done just as well to install it yourself. I've done 3 of these and they are a piece of cake. There's nothing to specially fit... just drop in parts. Not sure what was so difficult. But yes, the DCAEK kit is a spectacular upgrade to the M&P.
I did a review as well about a year and a half ago:
Glock 26 G4 | Glock 19 G4 | Glock 21 G4 | Glock 20 G4 | Smith & Wesson M&P 9 Pro | Smith & Wesson M&P 22 | Sig Sauer P220 Elite Dark | Sig Sauer P226 MK25
Daniel Defense DDM4 V4 | Arsenal SGL 21 | ASA SBR w/ Side Charger | Mega/PSA M4 Clone | Remington 700 SPS Tactical | Savage Mark II FV-SR
Mossberg 590A1 20" SP | Mossberg 590A1 18" GR | Mossberg 500 Cruiser