Ok, this wasn't supposed to be a general discussion, but I would like to point out a few items:
I also bought an Ipac a couple of years ago. I prefer it to the Keywiz because unlike the Keywiz it keeps its setting on power off and supports ps/2 and USB connections.
Agree on USB being a nice feature, however, the default codeset of both encoders is very good for MAME use and the default KeyWiz set is available after power-off, so it's not that big of a drawback, although it is a bit inconvenient.
However one thing I don't like about the Ipac is that some button inputs are shared with the keyboard LEDs. This apparently causes the shared buttons to become unreliable if the buttons are connected over a long cable. There is no mention of this problem on Ultimarc's site which is a bit disappointing. I've got round it by simply avoiding the 3 shared buttons. Unfortunately, this only leaves me 25 inputs which is barely enough.
Newer Ipacs apparently don't have this problem, but instead you see the LEDs flash briefly when the shared buttons are pressed. A minor issue perhaps but I'm a perfectionist.
I have heard scattered reports of this also. One point, I am pretty sure the LEDs flashed briefly when the shared buttons are pressed even on the original boards, so I wouldn't count on newer I-PACs not having the problem you mentioned. (And this is true of all the I-PAC boards: mini-pac, VE, /4, etc.)
I can't understand why anyone would buy a standard Ipac instead of the Minipac. The minipac is cheaper and has more functionality (either more inputs, or spinner/trackball support). OK it uses header pins instead of screw connectors but hacking an old IDE cable isn't a big deal IMHO.
Two reasons - First, the current Minipac can't use the new WinIpac IPD software.
Also, the current Minipac doesn't have more inputs. I agree hacking an IDE cable isn't a big deal, but here's an example where the I-PAC is a better choice than the Minipac -
Let's say you hook your panel up as
1 2 3
4 5 6
After it's built, you decide it would work better as
4 5 6
1 2 3
With the I-PAC, you could just re-wire the inputs and use a couple of longer wires if necessary. With the mini-pac, you really can't shift the wire locations on the IDE header end, so you would end up adding jumper wires to the buttons and possibly re-wiring the whole panel.
Okay, it's not that likely or serious, but still. . .