Im not a licsenced (See - I can't even spell it) electrician (personal
attackes from those who are are welcome), but it seems to you have
something out of balance with how the load is distributed from the
fused disconnect. (Your comments about 1 fuse burning; at least one of
the legs is drawing more than it should be).

Anyway - no, DO NOT replace it with a non fused disconnect, at least
until you find the cause of the problem and have it corrected.
Otherwise, all you are going to do is see or smell something else
heating up somewhere, probably followed by your house becoming
extremely warm.