Not to parse too finely...but I'd hesitate to say I 'recommend' anything. I relay my personal experiences with 'stuff' and what I've read others in-the-know to have said, but different riders have such a large variance of 'needs', I hesitate to couch my imos as 'recommendations'.
...besides....there is some responsibility inherent in recommending anything. Can't have that! ;)
That said, most aftermarket springs are coldwound. They have a considerably higher failure rate than hotwound springs. If they don't actually fail (I had a set that did after a couple of rides), they are not as 'resilient' as a hotwound spring.
If you take a coldwound spring and preload it at a very low number (like 3mm), you may very well end up with no preload at all in a short time due to the spring changing length.
If you maintain the forks as you should, this wouldn't be a huge problem..you'd be taking them apart for at least an oil change a couple times a year and you would notice the problem.
BUT...for those that service their forks every five or six years..well, you can see that minimal preloads on springs that may change length would be an issue.
Towit: I'd not put 3-5mm on a coldwound spring of any length.
But then, I wouldn't use the oem spacers on a 470mm spring either (35mm or so preload). Some do. Different voices, different choices.
Glad you like your preload change. Big difference, 'eh?