I'm still a bit puzzled by the mechanics behind the tech-stop calculations:
In a previous GW, I flew TPE-LAX with Tristars with a tech-stop while my competitors (4 or so) flew non-stop with B747s and MD-11s.
The route was a bit over-supplied and I applied a 10% discount to account for the stop. Result: ~90% load factor and good profits.
My CI was high and the ac type in general acceptable by PAX, so it worked. (Basically confirms what Talentz mentioned above)
In another GW, I tried: BOG-CDG with TU204 with one tech-stop and the result was very bad. My CI was about 80, the ac type a narrowbody
and russian on top of that (they get an extra hit) so it didn't work t all - and it shouldn't, to be realistic (I had no competition)
As I said, I'm not sure how it is coded: It most likely penalizes aircraft class "Large" and below while "Very Large" take less of a hit. Combined with "too small" factor and "CI" it gets complex and interesting.
It probably only needs more fine tuning for the early era and for ultra long haul where no alternative exists (to be fair, also in real life it's hard to
make money on ultra long haul routes, except with a very high ratio of premium passengers)
...just realized, I haven't added anything new or useful to this discussion haha.. but in essence I agree some fine tuning is needed

Cheers!
Mike