Ralph,
You may be right. However, the light emitted from under the neg may already be less than full spectrum, maybe...guessing? It would certainly be the case that a graded paper would only be sensitive to the bluish bit and a VC paper yellow and magenta. I'm out of my depth here.
If there was a Holga/Hassy difference, I would question the proper function of the older lens rather than the 'new level' performance of the APO, tho I have no doubt that it would perform supremely well. Tho some later designs may have greater contrast, this is nothing that a wee bit more contrast under the enlarger could not fix (mono). Barry Thornton reckoned that the sharpest 50mm enlarger lens he ever had was a 50mm f4.5 Minolta....which in a moment of madness he always regretted, he sold. I have one too, however, perversely, it does not come close to covering 35mm (must be faulty) - ouch, cost me £5!....My most expensive lens was £50 80mm F4 Rodagon (new, in clear out). This was £2 more than my 240 Componon S, which not having used it yet, I hope is a good'un. There are tons of cheap bargains on ebay if getting started!
Tom
Tom