Torsten, my goals are very similar to yours, and I started Oly lifting for the same reasons--I was going to do it for a while to learn the lifts, and then transition back to Crossfit.
However, two things happened: One, I fell in love with Olympic lifting. And two, I found out that doing Olympic lifting 4-5 days a week, with short, heavy metcons 2-3 times a week, improved my strength, conditioning, and overall fitness at a rate that was DRASTICALLY quicker than Crossfit. I cannot over-emphasize exactly how much more effective the combination has been for me than mainpage WODs. I have been doing this regularly for over six months and don't see myself ever looking back.
If I were you, I would do Oly-lifting mainly. Then, after your workouts (ideally four hours after, but I always do mine immediately after due to time constraints) pick a metcon that's on the short-and-heavy side, 10-15 minutes or less. I pick mine from the Performance Menu/Catalyst Athletics WOD. There's a "Short, Heavy Metcons" thread on the CF forums that has more ideas, and I heard the metcons on the CF Football site tend more towards the short and heavy end as well.
If you are feeling your endurance suffering, then make one of your 2-3 metcons a week one of the longer types. But give that programming a try for a couple of months and see how it works for you.
(I also see now that you're interested in gymnastics, so maybe throw that in a couple of days a week in lieu of the lifting if you so desire)