You would be sacrificing a much larger FOV, more transparency, sharper edges and a much lighter and smaller binocular for a few extra minutes of observing time at sunset. 98% of the time when you are birding during the day the 32 mm alpha will give you a better view with a much wider FOV and superior transparency, and it will be much lighter and more compact to carry ALL day, except for the maybe fifteen minutes when the sun is going down the bigger 42 mm Conquest HD or Razor would be slightly brighter because of the bigger exit pupil. You have to decide, is that 15 minutes worth it to you?