I would think you would see some improvement versus a 2003 frame in the weight alone....however, is the geometry the same? Will it fit you, will you like the geometry of the focus compared to the Allez? Only you will be able to tell
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Brian | 2023 Trek Domane SLR 7 AXS | 2023 Trek CheckPoint SL 7 AXS | 2016 Trek Emonda ALR | 2022 Trek FX Sport 5
you should learn to embrace change, and mock it's failings every step of the way.