Let me preface this response with "THIS IS MY OPINION" and you are all welcome to post your own feelings...
The Luger IS a strong action compared to its competing contemporary designs, but the reality is that these original weapons are mostly between 50 and 100 years old and they were not designed to handle the pressures of ammunition in the +P category.
Steel can become brittle and work hardened with age and I for one would not subject ANY gun that I own to a steady diet of the hot stuff. Use of "standard" loads should preserve your Luger for generations to come and it will suffer only "normal" wear and tear. Just like my 55 year old body... If I abuse it, I can expect that it will be hurt. Appreciate your Lugers for what they are... a piece of history, and while they can be repaired or have parts replaced... they will NEVER be the same or original after being abused... so I don't.
As far as jamming... The Luger is finicky when it comes to magazines... but once you have a magazine that functions well with a particular load, you can expect that your Luger will function reliably when properly lubricated and used with appropriate ammunition. If this were not so, they never would have been adopted for military service by so many nations.
Just my $0.02
