I decided I need a tent which is 1) reasonably light for mountain hikes 2) small to pack for family hikes (our son tends to stuff his backpack with toys... but then he's 4 so that's fair enough!) 3) reasonably simple to make 4) double skinned - in Scotland, where we live, you get a lot of condensation! Finally, I didn't expect this to be totally bullet proof - this is mainly for family hikes with a 4 year old, so not really need it to withstand high winds high up on a ridge or loads of snow.
To save on packing space, I decided to go for a design that uses walking poles as structure. It is based broadly on the Hilleberg Anaris and a few similar designs, but it is a bit longer so that it can comfortably fit 3 people.