To Keep the hacking thread clean, I´ll carry on here.
Done the "upgrade" Thing, before I took a pic from the 70Mhz BW while the 40ps pulse-gen. was running:

(Unfortunately forgotten the 50

Termination)
Now, with 350Mhz BW:

Quite "faster", but somewhat of a "glitch" into it.
Compare it with lecroy WS3024, first with 1M too:

Looks "better"...
Now, with a 50

external termination resistor, rigol:

No "glitches", really fast (under 1ns) but massive overshoot...

Hm, hm....test it with the same resistor on the lecroy:

Aha, same on the lecroy..

Now, with it´s own integraded 50

termination:

Ahh, perfect....

And external termination as needed by the rigol is just crap.
Ah, some more about the problems, in this case a forgotten thing :
Functiongenerator, decreasing/increasing the amplitude : There´s no choice between Vpp or Vrms, it´s only in V....