Today I experimented an old 2-line kite of 3.75 m² and 4 m span, wind 5 to 10 m / s. Operation was correct despite wear, still pulling strong at the zenith.
Loops were about 3 to 4 wingspans (12 - 16 m diameter). At the end of two loops the kite was already largely lowered. So I think I can say that the passive descent while turning is not a good solution because the kite goes down too fast. A swash plate in @someAWE_cb style for control could perhaps be adapted, or something simpler and a swivel.
I continued the tests until I had to let go of a handle because of the pull too high for me (and for one of the two bridle knots that went off) during a loop, and comparable to that which resulted of a long trajectory as achieved in a figure eight.