071 are fine, a very good versatile plug that will do the job perfectly, just not as perfect as some others, the IK range are made by Nippon Denso, they have a iridium centre electrode, and take less voltage to create a spark, despite iridium being a bad conductor!!
My experience of iridium plugs is a better more stable idle, smoother running, and just seen generally more eager on them, the downside I found is they hate being fouled and often throw in the towel if sooted, even once cleaned often don't work 100% again, but so long as mixture correct isn't a problem, around 4x the cost but worth it imo, others may not agree, it is a lot of difference £10 or £40, so I can see their point, your choice really.
I'm using 071 for running in, but will change around 1500 miles.
tabetha