I have heard the saying so often "Life is Too Short for QRP". For some reason, many radio amateurs refuse to embrace and even eschew low power (I mean really power - 5 watts or less). In their minds, you just can't work much DX with that low a power. That is definitely true if one does not have efficient antennas, or lack of knowledge of propagation. If you have worked your entire ham career with 100 watts or more, your habits are most likely going to affirm that 5 watts is simply not enough power.
I was a part time member of the school of thinking that. "The more watts, the better". I go on further and quote top of the honor roll member Dave K4SV, "It's not how big your watts are but how big your watts appear on the other end". In fact I keep two sets of books - unique DXCC's that I have worked QRO, and unique DXCC's that I have worked QRP
But as you progress and mature and gain experience as a ham, you begin to realize that it's not so much the "watts" as it is what you do with the "watts". Brute power isn't the end all and be all. Operating skill, knowledge of propagation, patience and perseverance - these are what get the QSOs and the DX in the log! And specially rewarding is getting those QSO's with a mere 5 watts.
I've mentioned in several places that I've been licensed since 2009 and started chasing DX in earnest in 2011. I started my HF career as a QRPer because that is all I could afford at the time and my first rig was with the venerable Yaesu FT817., I have always been attracted to and have dabbled with operating with low power ever since that first QSO with VK6LC, Mal, in Australia on phone with my FT-817. I joined QRP ARCI and NAQCC and participated in a lot of QRP activities including pursuing my first ARRL QRP-DXCC certificate which I acquired in 2012. I decided to take a hiatus from QRP in mid 2013 and bought my first linear amplifier - a Drake L4B, from which I can generate 500W output easily with 50 watts drive. Since that fateful day in August of 2013, using that linear, I racked up enough unique DXCC's to get 8 Band DXCC (and the 5 Band DXCC Plaque), DXCC Challenge, and 301 confirmed DXCC. Now that the remaining unique DXCC's have thinned out, I have gone back to operating almost exclusively QRP. In fact, I'd dare say that since my QRO days, I've had the most fun I've ever had as a Ham and continue my chase towards 200 DXCC QRP (currently at 159).
Here are a bunch of stats using Qscope that demonstrate that QRP indeed works. The first image is based on 8144 QSOs which were combination of QRP and QRO but mostly QRO. Antenna setup is the same for both situation. A Hexbeam for 20-10, ZS6BKW mainly for 40 and a vertical for 80. The QRO stats are over 6 years of data and the QRP stats are only for 2016 year to date.
How does the above compare to QRP below? Interestingly enough QRP has just as much reach and if anything - on a percentage basis there are longer distances with the QRP QSOs. The comparison is clouded by dupes but interesting nonetheless. The QRP contacts are more evenly distributed azimuth-wise with large concentration to EU, Oceania and Carribean.