hook load capacity

Recently I was thoroughly owned in a debate over at PTR (thread 'drilling costs to plummet) about whether or not the GT3000 and/or the GT5000 could drill production wells for geothermal energy. I thought that was what they were designed for, but apparently I was wrong.

What came out of that debate was that 'Don't get too excited about the 'new' drill tech, the GT's could never drill deep, wide (7 inch at bottom) production holes to 4km like PTR are drilling because their hook load capacity is too small at 154tonnes (GT3000) and 200tonnes (GT5000 estimated) to safely pull the drill string at depth if anything goes wrong.'

I could find 5 or 10 statements in the GT3000 brochure and other CKK material that would seem to contradict that, but this guy had drilling experience and he was adamant.

In fairness, he did seem quite keen on the drill, because it could do slim exploration so quickly and cheaply, so he said it would get plenty of work in geothermal because slim exploration holes are still a big cost.

That said, some of the geothermal work coming up only involves drilling to 2km or so for production(Panax's volcanic geothermal play in Indonesia, for example.)

So my questions are, is it true that even a GT5000 would not be able to drill and case a 7 inch geothermal production hole, no matter the depth? To what depth could a GT3000 drill and case a 7 inch at bottom geothermal production hole? To what estimated depth could a GT5000 drill this size production hole?