Get the GP. You said it yourself; you have a history of letting cars become garage queens, and that's no fun. Buy the car you'll drive...
As a past BMW owner, there's always this question of vanity involved when considering cars other than BMW. Whether it's "what will people think?" or "I deserve a BMW!", the brand has been so pumped-up and made synonymous with success and money, that people buy them for the wrong reason.