Have to say that I'm with Steve on the new Ecover - I tried it myself as I can't resist any products on the shelf that say New & Improved on them. Rinses down the dispenser completely unlike the last lot of Ecover powder I tried about a year and a half ago, and does clean whites somewhat but can still leave heavily soiled whites dingy, though admittedly most of the stains do get washed out. I have also been using a skin friendly detergent in the UK called Filetti, which is made by Henkel. It seems to be very concentrated too, I have hard water and I only use 100ml (rather than the recommended 275ml for my area), and I got dazzling whites. Rinsed out superbly too.
My mum uses non biological products most of the time (she uses either Persil Non Bio, Ariel Sensitive or Fairy Non Bio - she's using Fairy at the moment) and all three seem to perform similarly, though she always keeps some biological detergent in stock to clean tough whites and that which the non biological detergents can have a tough time with. I've tried switching her to more sensitive powders such as Ecover or Filetti, but she's a fan of bulk buying and likes to buy her detergent in huge boxes (as you've probably all seen in pictures of our utility room). She uses Comfort fabric softener too, but only because I switched to Ecover fabric softener and I'm running down my stock of Comfort downstairs, and once that's all been used up I'll probably use Ecover down there too.
Another great detergent I've been using recently is the Aquados powder capsules - they don't have as much ingredients inside as Ariel, Persil, Bold etc but still do a good job - better than Ecover and about as good as Filetti, and gets white as white as a hefty dose of Persil and Ariel can, and they rinse out superbly too.
I think though in terms of skin problems, as long as the washer is a decent rinser then you shouldn't really have massive skin problems. My sister & dad have said they both have noticed their skin has gotten better since we got the new Miele (the Bosch was awful at rinsing), and I can also use Ariel in my AEG or Miele whereas in the Bosch or the old Hotpoint, if I ever used biological Ariel, or Bold I would itch like hell.
In terms of low water levels - I have to say I've never had a problem with whites and a low water level. In fact I believe that a lower water level cleans better, as there is more tumbling action whereas most of the tumbling action is muffled on the higher water level delicate cycles (which is actually the purpose of the higher water levels on delicates, the tumbling action is muffled to provide as gentle an agitation as possible). Rinsing is another thing though - on most washers a high level rinse is more desirable as low level rinses don't rinse too well especially when compared with half hearted interim spins (like on my nana's Hotpoint). Both mine and my mum's Miele only do 2 or 3 rinses, but fill slightly higher than low level rinses but still a considerable amount less than a deep rinse (although still only to just above the door seal) and spin fast between the rinses and even 2 rinses can rinse out detergents such as Fairy great, leaving no smell - something the Bosch couldn't do with 4 low level rinses! I've found that the 2 rinses haven't been a problem at all with Ecover or Filetti either, I suppose these are designed to rinse out better and the last rinse water is always clear - although still slightly foamy in the last rinse if you use fabric softener as with any washer. This has led me to believe that provided it is done correctly, washing machines *can* rinse well using a small amount of water, but it has to be done correctly otherwise you end up with poor rinsing like with my nana's 2005 Hotpoint-Ariston.
Of course, you still can't beat good old deep level rinses for the drama

. But with the ever growing problem with water we're at least experiencing in the UK, with half of the UK in drought conditions, then there does come a point where you have to cut the thread short and economise on resources.
Anyway that's another Jon rant over, take care all
Jon