This thread originally posted while I was incommunicado.
For he who is willing and able to do the work him or herself, GR Research offers an upgrade kit for far less than $4000. The kit also includes a cross-over that "corrects" the frequency response imbalances Maggies are inflicted with, which the X upgrade leaves uncorrected. The GRR kit also bypasses the fuse block (with all it’s ferrous parts), which I assume the X upgrade leaves intact. The GRR kit obviates the need for the fuse, even on the Maggie ribbon tweeter.
Let it be known that I am no Maggie hater; I bought my first pair in 1973 (Tympani T-I), and currently own a pair of Tympani T-IVa.