Walther LP400
I'm afraid I also don't have any experience with the Hammerli Pro- but I recently upgraded my vintage(?!) Steyr LP1, my first match pistol to the LP400 carbon and I am very pleased with it indeed, it is a fabulous pistol. In reality, all of these pistols will probably shoot better than you or I but the better the pistol, the more adjustment and room to grow as it were. I would definitely recommend the Walther. Superb!
Steyr Evo 10, Anschutz 8001, BSA Scorpion SE, BSA light Pattern, HW77k, HW30s, AA TX200, HW45 Blackstar, HW40, Walther CP88, Webley Premier E, TBC!