You say “reversible computation can implement PSPACE algorithms while conventional computers can only implement algorithms in the complexity class P.” This is not true in any interesting sense. What class a problem is in is a statement about how fast the space and time increase as the size of the problem increases. Whether a problem is feasible is a statement about how much time and space we’re willing to spend solving it. A sufficiently large problem in P is infeasible, while a sufficiently small problem in PSPACE is feasible. For example, playing chess on an n by n board is in PSPACE. But 8 is small enough that computer chess is perfectly feasible.
You say “reversible computation can implement PSPACE algorithms while conventional computers can only implement algorithms in the complexity class P.” This is not true in any interesting sense. What class a problem is in is a statement about how fast the space and time increase as the size of the problem increases. Whether a problem is feasible is a statement about how much time and space we’re willing to spend solving it. A sufficiently large problem in P is infeasible, while a sufficiently small problem in PSPACE is feasible. For example, playing chess on an n by n board is in PSPACE. But 8 is small enough that computer chess is perfectly feasible.