Errmmm...
...not exactly. I think what I did say was that detergents still cause foam into the final rinse in spite of using a high-level rinse machine even with hard water. Bear in mind here that I am dosing for hard water so using more detergent than someone with soft water. Perhaps if I cut that dose in half I'd have fewer suds, but having seen the detrimental effects on a machine of light-handed dosing in hard water, I'm not about to start doing that.
I'd warrant that having soft water does make it harder to rinse in terms of knocking back the suds, but as to whether clothes are any better rinsed in hard water is tricky to say. For example, if you took two identical loads of washing - one washed and rinsed in soft water, the other in hard - then agitated each load in a tub of plain warm, soft water, would we see the same amout of sudsing from detergent residue, bearing in mind the load washed in hard water would have had more detergent used on it?
Perhaps we should also consider whether suds are the ultimate indicator of rinsing performance too. Who's to say that a detergent that doesn't foam is leaving any less residue on the laundry?
Good luck with your specially formulated detergent anyway. It has to be said that P&G's UK powders are generally more sudsy than others, just for the record.
And as for TWIN TUB RINSING, well...tried it twice and gave it up as a bad job after that! I'll probably give it another go at some point in the future though.