Is there any mainstream criticism of the Benes-Kumhof conclusion that the Chicago Plan would improve the US economy nowadays?
On the Equivalence of Private and Public Money is a 2019 working paper by Brunnermeier and Niepelt that addresses this issue:


  We propose a generic model of money and liquidity.  We provide
  sufficient conditions under which a swap of private (inside) against
  public (outside) money leaves the equilibrium allocation and price
  system unchanged. We apply the results to Central Bank Digital
  Currency,  the “Chicago Plan,”  and the Indian de-monetization
  experiment.


This is their exercise:


  As a result of these developments, debates about the “right” monetary
  architecture resurface and classic questions about the nature of money
  return to the fore.  A key point of contention concerns the optimal
  balance between public and private money. Proponents of a strong
  government role fear that private money creation breeds instability
  and shifts seignorage rents from taxpayers to shareholders.  In the
  “Chicago Plan” of the 1930s and the  recently  rejected  Swiss 
  constitutional  referendum  on  “Vollgeld”  (sovereign  money), they
  propose to severely restrict or even ban money creation by anyone
  except the central bank.  Less drastic proposals aim at electronic
  Central Bank Digital Currency (CBDC) for use by non-banks.  Monetary
  authorities in countries such as Canada, Singapore, and Sweden
  currently evaluate the introduction of such “Reserves for All;” the
  Banco Central del Uruguay has successfully tested the model; and other
  central banks consider it.
  
  Skeptics, on the other hand, warn of severe macroeconomic risks due to
  the replace- ment of private by public means of payment.  In their
  view, a reduction of bank issued inside money will hamper credit
  extension by banks to firms and households, with negative
  implications for growth;  and the introduction of CBDC will provide a
  safe haven asset for depositors to run into at the slightest hint of a
  crisis, rendering bank runs more likely and thereby threatening
  financial stability.
  
  To assess these arguments, we develop a generic model of money and
  liquidity.  Within this framework, we establish sufficient conditions
  under which it is irrelevant whether the public  or  the  private 
  sector  issues  means  of  payment.


They summarize their results as follows:


  We  apply  our  results  to  two  proposals  for  monetary  reform: 
  CBDC,  and  the  more drastic “Chicago Plan.”  We find that the
  introduction of CBDC need not change macroeconomic outcomes,
  independently of whether deposits are subject to bank runs or not.  If
  bank runs are a feature of the current system then the equivalent
  monetary regime with CBDC has state contingent transfers from the
  private sector to the central bank; if it does not, for instance due
  to a generous deposit insurance scheme, then no such transfers are
  needed.
  
  Contrary to the prevailing view that CBDC would make bank runs more
  likely, our analysis concludes that it might well make them less
  likely.  With pass-through funding, the central bank becomes a large
  depositor that internalizes run externalities, unlike small
  depositors.  This makes the financial system less fragile. Regarding
  the Chicago Plan, we also find that the conditions for equivalence are
  met provided that banks receive appropriate compensation for lost
  seignorage rents, or that the  ownership  structure  of  banks  is 
  aligned  with  the  distributions  of  tax  burdens.   An important
  motivation for the “Vollgeld” proposal to outlaw banks from creating
  liquid assets  was  that  banks  should  be  forced  to  relinquish 
  these  rents.   This  would  transfer seignorage from bank
  shareholders to taxpayers, undermining wealth-neutrality.
  
  We also apply our results to the recent Indian de-monetization
  experiment.  We find that it could not have been neutral because
  cash-based transactions at black-market prices could not have been
  replaced by deposit-based transactions.


In contrast, there is a Bank of England working paper that strongly disagrees.The macroeconomics of central bank issued digital currencies by Barrdear and Kumhof (2016):


  We study the macroeconomic consequences of issuing central bank
  digital currency (CBDC) -- a universally accessible and
  interest-bearing central bank liability, implemented via distributed
  ledgers, that competes with bank deposits as medium of exchange.  In a
  DSGE model calibrated to match the pre-crisis United States, we find
  that CBDC issuance of 30% of GDP, against government bonds, could
  permanently raise GDP by as much as 3%, due to reductions in real
  interest rates, distortionary taxes, and monetary transaction costs. 
  Countercyclical CBDC price or quantity rules, as a second monetary
  policy instrument, could substantially improve the central bank’s
  ability to stabilise the business cycle.