Briefly: No, no, depends if you only fly economy or also business, I think both programs are a major pain to redeem with (no online service), no (well, OZ technically does but only on OZ metal).

If you only fly LX (or LH) within Europe you might stay put, since FTL gives you access to LX/LH business lounges anyway. Otherwise, you might want to consider an "investment" and do a mileage run to make SEN, match SEN to TK*G, fulfil the requirement to extend the *G, and then maintain that. Check out the status match thread in the TK forum.

Look carefully at what booking classes you have flown over the last 12 months and simulate how many miles you would have *actually* earned in the two programs before you take the plunge.