I never thought to use radishes - must give them a go now that you say the 'bite' goes after cooking. I have tried all the myriad versions of cauli mash, too and hated every one - plus it seems to have a poly belly effect on me, too!
Turnips, or swedes as we call them, are fine as 'turnips', but trying to make them into something dry, bland and floury like the spuds we eat here in Ireland is a wasted effort.
Thankfully, I can order Dreamfields on the net, so I can have pasta a couple of times a week. I heard they were working on a potato sub ages ago, but no sign yet. The new season's potatoes (gorgeous) will be available here soon - pre-diabetes, I could eat just spuds and butter for my dinner!
Thanks again for your help - I will let you know how I get on.
Babs