£1500 for a dream bike? Pah - I once spent $16,000!
I don't see how a ti bike can be a bike-for-life. What if it needs repairing? Ti welders are dashed hard to find. You need something which can be repaired by a British framebuilder.
With your money I'd start by picking an ultimate steel tube set by asking Dave Yates. I'd ask what the point of 953 is. OK, it's stainless, but it will still need painting to cover the silver solder won't it? So I don't see how you can have a stainless steel look. And if 853 is properly rustproofed it will last forever. So I wouldn't get 953 unless it gives a better ride. And I can't find anything on the web to say that it's definitely lighter or stiffer than 853 Pro Team. Anyway, because Dave works with anything he might suggest, say, Columbus Spirit. 0.38mm wall thickness - how dreamy is that! http://www.framebuilding.com/Spirit.htm
Another option is to go on Dave's course and build it yourself - that's a dream come true! And yes, you can build it in 853, no problem. An unpainted frame would be around about £795 for the course and about £250 for materials.
Then I'd spend the rest of the money on an insanely beautiful paint job. And transfer my existing components across to the new frame. And start saving for some Carbonsports Lightweight wheels