haven't seen comments that Type XXIII was useless or have major issues, other than small torpedo capacity. my point overall is that it would have been a more suitable project (coastal defense or simply recon. on Allied moves ... at that point) and more suitable project to build (as it consumed less resources to build, operate, manpower.)
you are postulating that an early end to u-boat construction would benefit by diverting those resources to other more useful weapons programs? would agree up to a point that continuing the same Type VII was fruitless or diminishing returns? I'm only substituting a compromise solution that allows a more limited u-boat war to continue. recall the Exercise Tiger disaster https://en.wikipedia.org/wiki/Exercise_Tiger , with small Elektroboot they might have been able to disrupt some Allied operations in ways that mortars and AA guns could not.
would suggest reclaiming resources for more productive or needed weapons should have looked first to V-2 project and/or streamlined flak operations (as they had tens of thousands of AA flak sorely needed on Eastern Front and their use against Allied aircraft was questioned at the time.)
Maybe another problem was trying to perfect the Walther drive - effectively trying to be revolutionary instead of evolutionary?