Olivia,
Sort of like the Whole Sign chart is who you would be if conditions were perfect and the quadrant chart is who you actually are in the less-than-ideal circumstances in which we live.
I cannot agree with you more on this point. I've always used Placidus only because that's the default in astro.com. But when Robert Hand read my chart and used Whole Sign, I was totally blown away. He was able to find all the explanations (that I had by using Placidus chart) using Whole Sign chart. Regardless, I'm still not convinced at all that Whole Sign chart is my "current" chart.
Because my chart has a stellium of 4 to 5 planets, and that I have a very late degree ascendant, I think it should be easier to pinpoint the choice of House. If I use whole sign, 9th House activities are truly who I am or was born to. I LOVE studies of everything so much, especially science/astrology/religion/anything that tells me more about universe. However, based on transits through Houses in both charts, I really think that Placidus explains things much better for my life events. For example,
1. Pluto transit through my 10th house (in Placidus) from about 1987 Nov to 1997 Dec, the timing is fairly correct in that I started a tremendous effort in studying sciences from my high school until my second Master's degree. This timing would not be correct for whole sign house system.
2. Uranus transit through my 2nd house (in Placidus) from about Feb 2004 to 2013/2014. My net worth is going UP & DOWN so much such that many times I gained or lost 10 years of my annual savings in a month. If I use whole sign, Uranus would be in my 3rd house. But in no way that my Uranus transit through my 2nd house is over.
3. And the last Saturn transit through my 8th house in Placidus (where I have the stellium) was simply horrendous. And the events involved were such a joint-finance 8th house matter, and it is simply unmistakable IMO.
4. I have Jupiter transit thru my 2nd house in Placidus right now, and it appears to be quite correct. Again, I just cannot explain it if I use whole sign 3rd house.
I kept trying to come up with some wacky theory to reconcile the two house systems, such as having the whole sign house to move 1 degree every year of a person's life. I almost thought that by that it would explain Solar Arc or Progression of Sun changing signs simultaneously, except that this movement of house division is in the exactly reverse direction of Solar Arc. Since my Sun is at about 15 degree, I didn't realize this initially.
Regardless, my stellium has grown & "moved" from 9th house whole sign into 8th house Placidus over the years. If simply judge by the amount of time that I spend every day, I AM a 8th house person now.
By the way, I have Pluto trine Mercury now, studying astrology crazily. Somehow astrology really works, although I'm not sure why.