Working DX contacts is rarely a good indicator of how well an antenna works on 27 MHz.
Mother Nature rules the roost when the band conditions are open.
Many many years ago I got hooked on DX when I had a 23 channel Midland SSB radio and a radio shack mag mount stuck on top of a cooler that was on top of the mobile home I had.
Stock bare foot radio, no Amp, no peak and tweak, the cycle was up and the band was blown open almost every nite. I consistently talked to a guy in Montana over a period of several weeks.
That radio was not capable of more than 15 to 16 watts peak on SSB.
And I am also sure that mag mount was not that efficient.
On another ocasion we were staying at my in-laws place for several weeks on vacation.
I took a radio, a 100 watt amp and MFJ antenna tuner with me.
Hooked to the 300 ohm twin lead feeding a VHF/UHF TV antenna on top of the house I worked all over with that set up for the whole time I was there.
The radio was seeing a almost flat swr.
The tuner was working into high SWR.
The effective radiated power was I have no idea.
All of that was actually the twin lead going to the TV antenna at that point.
But it worked well enough to talk both to the locals and DX.
The antenna can be terrible, but if the band conditions are good, 27 MHz can be worked with very small amounts of radiatied power.
Ask the guys who play QRP for fun.
This is why I love 10 meters so much.
Same property's as 11 meters.
And 12 and.
..... So on.
73
Jeff