@Salvia I've only seen the Hass variety too. Interesting that your Sainsbury's avocados were from Colombia. I've only seen Peruvian avocados in my local Sainsburys, I've tried them and they have varied, the Waitrose ones are usually better and more consistent. I'll watch out for the Colombian ones and give them a try if they get any in.
Let us know what the Aldi Tanzanian one is like. There is an Aldi not too far away from me.
Will do on the Tanzanian ones. I haven't located a Waitrose within reasonable driving distance, but will keep looking (though I don't propose to scout around any great distances!)