I bought my Mark IV from them a few years ago and it took many months before I got it, but they told me up front that they were really behind in getting the machines built. They only had one person at the time doing calibrations.
I could only ever reach them early in the morning by phone and typically had to leave a message for them to call me back. I haven’t had any issues with orders I placed with them, except that their website isn’t up to date with what is actually in stock and things overall seem to take a long time to ship. I placed some orders by phone when they called me back and others on their website only to be notified that much of what I wanted was really out of stock.
I would order from them again but only if I wasn’t in a hurry to get stuff and I couldn’t find it elsewhere.