Hi Marco,
I'm just collecting knowledge to evaluate pros & cons of each option.

So you say:
* low compliance cartridge -> JELCO 750D
* middle/high compliance cartridge -> SME 309
Right?
That makes sense to me, too. And, yes, I can stick with DL 103 for a long while.

Jelco was my first idea, but, TBH, there's one thing I just don't like of Jelco: the way of adjusting the VTA is not easy like the stock or the SME tonearm.

Ok, I have to add an external VTA adjuster.