Very well explained. would you not have the problem of the spliced line (2mm to 3mm) moving around the net ?...ill explain..if you splice the 2mm to 3mm and it is one continues loop (which it should be) eventually the line creeps around the net..only a bit at a time but over a season your splice may have started off at your end pin and could end up 30 yrd in any direction from that pin....that's why imo the running line should be one size only....this is not a dig at you banter as you have given a good enough reason as to why you've done it.