The general attitude of this website is that KMiles are best spent on flights rather than upgrades. Logic would also suggest that the best flights to spend them on are Air Malta flights. However, this is not necessarily the case.
I have noted on numerous occasions that you can now spend KMiles on Lufthansa flights.
So, before you redeem your KMiles, I strongly recommend that you visit the Redemption page of this website and have a look at the Air Malta and Lufthansa “points redemption tables”. It may well be that you get considerably better value spending your KMiles with Lufthansa (for example, an Air Malta return business class to Dusseldorf is 85,000 KMiles; a Lufthansa business class return to Dusseldorf is 60,000 KMiles).
You hugely undermine your hard work in collecting points if you do not redeem them properly, or get poor value in redemption, so please ensure you regularly consult the Redemption page, which aims to guide you on how best to spend your points.