Exhaust thrust is not an issue at low power or cruise power. The only time exhaust thrust is important is at rated power or WEP, when all the power and speed you can get is what is needed.
Exhaust thrust depends on several factors including exhaust mass and volume. Another one is the shape of the exhaust manifold / pipe / pipes. If the area starts at the exhaust exit and decreases gradually to the end of the pipe, the exhaust increases in velocity, much as air does through the front half of a venture tube. It is usually called an "ejector" exhaust. That ALSO increases back pressure. SOME back pressure is needed for highly-tuned engines and exhaust systems. If the pipe starts at the exhaust exit and then slightly increases in area, then the exhaust velocity is reduced a bit and thrust is not likely a factor. If the area stays the same all the way down the pipe, then the exhaust velocity depends entirely on the exhaust mass and speed coming from the exhaust valve. The Mistubishi Zero had exhaust ejectors and they helped top speed by some 10 – 15 mph at full throttle and at critical height. Probably didn't help much at takeoff or lower throttle settings.
I am not an expert on German engines, but the performance at altitude also depends on the supercharger gear ratio, impeller diameter, number of impeller blades, impeller design, smoothness of the stator intake and exit from the supercharger, and the shape and efficiency of the intercooler if so equipped. It is difficult to believe all these factors were identical for two engines developed by different companies, but not impossible. Probably one or the other had advantages, even if slight at particular heights. At max height, they could well be almost equal, so the nod SHOULD go to the one that is more reliable, with the better time between overhauls, and/or ease of maintenance service … in no particular order.
The Jumo 213 was perceived as a "bomber engine" by Kurt Tank and he told as much to the fighter pilots, but it gave yeoman service in the Fw 190D-9. It was a better engine than either the designer OR the pilots expected.