I could not agree with you more. I have summitted Whitney 10 times with all but one being a Day Hike. Last year was my first overnight and it will not happen again. Carrying a 30-40 LB pack, setting everything up, enduring a "cold" night and hearing people passing your site in the wee hours makes for an unpleasant experience. Remember, you also have to carry that pack down "after" summitting. I like to enjoy the descent with little weight
Put in 4-6 months of "serious" training and enjoy the 10-16 hour Day trek.
