The Dichro 45 microprocessor controlled head is the notorious one. A tech described it as having a ticking time bomb of a board, after a while they burn out and Beseler no longer supllies parts. Richard Davies (ADRIANANDJILL@worldnet.att.net) has designed a replacement but I don't think the head is worth the cost.
The Beseler Minolta 45A does have one bug I know of and it's more operator oriented. Sometimes it doesn't work and you have to reset the computer with a pin pushed into a hole on the board. Many owners don't know about the reset switch and are mystified and annoyed when it abruptly quits. Other than having to keep fresh flashtubes in it to work the best it works as advertised.