Yes, kicking the rear of the arm outboard always did make me wonder if running the front and rear bushes out of parallel has any adverse affects. It doesn't seem to as I've run Whiteline and SuperPro ALKs for the best part of 8 years.
The whiteline ALK failed after 3 years. Both bushes suffered from the usual polyurethane problem of 'creep and set', which basically means the hole in the bush ovalised, allowing unwanted lateral movement. Rubber doesn't suffer from that problem, so consequently lasts longer.
Ignore the Castor claims. The SP ALK claims +1 deg castor but in reality it was the same 7.5 degrees as stock on the alignment rig. The main benefit of the ALK kits is to replace the soggy OEM voided bush with something stiffer for better steering response and feel. The proper way to gain castor is tilt the strut back mechanically, but you need camber/caster plates for that.
Additional castor gives stronger self centering and more dynamic camber when cornering. It does indeed make the steering heavier also, which some folk like
If I did all again, I would just press Lemforder S3 bushes into stock console housings and be done with it
