I think it depends. If you are out in the water and need to furl the 150, then I would do that. If you are going out for the day and you know that you will need to shorten sail, then I would take the trouble to change the sail. I can't find the picture of a race day with my 150 furled and it just looked ridiculously bad and our performance was miserable accordingly.
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Here's my very, very old 110 on a day when we knew we would be reefing. I think it actually looks pretty good. It certainly isn't embarrassing like the picture of my furled 150!
(I'd show the picture if I could find it right now).