As a 30 Luger shooter I can tell you that it does take a different recoil spring. (I shoot it in a Ruger P89 as well as Lugers, both take a different recoil spring.) This is doubly so, given that current factory ammunition is underloaded. Winchester claims 1250 fps for their ammo from a 4.5 inch barrel but the air over my chrono must be thick stuff because I can't get close to that from any of a multiple of guns ranging up to a 6 incher. Fiocchi's stuff is slower still.
The urban myth that a 9 mm Luger wants hopt ammo is just that, a myth. But it does have a different recoil spring than the 30. Not just because Georg Luger and God intended it that way but, but because of the urban myth, every Tom, Dick, & Harry has been tinkering with the recoil springs in shooter grage Lugers. Open up 7 shooter grade Lugers and you will find 8 different recoil springs, 9 of which are out of spec.
There are various reasons why the Luger has a poor reputation for reliability, most of them BAD reasons arising from ignorance of what a Luger needs to work right. But lack of hot ammo isn't one of them.
On the other hand, the 7.65 Parabellum is sentimental favorite of mine. The bottle necked case does feed better and I've been known to run cast semi-wadcutters and full wadcutters with perfectly good reliability.