Womble - you don't need all that many spud plants to be self sufficient in them. I grow rows 20 plants long. Last year I grew eight rows and that was far too many for us, including plenty sold and given to our offspring and their families. This year I grew five rows and that seems a better number, so that's a plot only 12' by 30'. Then you grow your brassicas there the next year, and everything else the year after, then back to spuds. So you need a plot 30' by 36' to be self sufficient in everything and have a good rotation
Blight is a big problem, especially as it keeps mutating so spuds which are resistant one year may be affected the next year. Lady Balfour is a nice potato which used to be resistant to blight but isn't any more. Cara is resistant and very tasty but even that has some blight this year.
The Sarpos are the new 'wonder spuds' but like you I find them tasteless and coarse, at least the first ones developed. I'm growing 20 Sarpo Mira this year, but the first 3 plants in the row have succumbed already.
There are some spuds which simply disappear with blight, leaving nothing anywhere - the special roaster I was growing last year did that, but there were plenty of others to fill the gap.
I agree that the kits are a waste of time unless you have nothing more than a small patio to grow on. Same with those tiny raised beds which cost the earth and grow four cabbages, or whatever. I am lucky to have good soil so I grow everything direct in the soil, no beds, no containers - but masses of weeds