The government bears most of the risk of error in a criminal trial: factual error because of the requirement of proof beyond a reasonable doubt and legal error because of the prohibition on government appeal of acquittals.
An important consequence of the asymmetric risk of error in criminal cases is that there are more acquittals than there would be under symmetric risk of error, ceteris paribus.
That is, assuming all other rules of criminal procedure and evidence remain the same, more defendants would be convicted (by guilty plea or after trial) under the civil standard of preponderance of the evidence than are convicted under the reasonable doubt standard.
Similarly, if appeal by the government were allowed, some acquitted defendants would suffer reversal and be convicted at a retrial.