I did regret getting a single sided power meter. I was having a lot of trouble to hit the required power on some intervals because my left/right offset is not constant. When I need to push high wattages at high cadences my left leg starts to slack compared to my right leg, which means that when TR wants me to hit 300w, I really need to hit 315w so the left sides power meter can reach 300w. This was really affecting my training so I recently upgraded to a dual sided one and not only that problem went away, but also is now much easier to hit and maintain the required power at all intervals.
In the end, I would say that one sided power meter is much better than virtual, but there is a significant jump from one sided to two sided.