The Eison 1440 lathes of similar specs are made in the same factory as the 1440GT. The difference of the 1440GT is the head stock was specially made to QMT's specs to have a 2" bore and D1-5 spindle. It is my understanding that the steel stand is also custom spec for QMT. The 1440GT is unique in it's class for a Taiwan made lathe in that regard.
I think the G0709 & G0509G are a lot of lathe for the cost as the base price is low and they include a lot of accessories. The QCGB is also a big plus. I have not had the opportunity to see a G0709 but I have fiddled with a G0509G and was impressed with what you get for the cost so it was on my list.
3 phase / 3 HP was my limit due to power limitations and physical room. Another consideration about going larger than the 1440 size is everything gets bigger, chucks tooling etc. An 8" chuck is about all I want to handle without a lift.
The "heavy duty" 1440's will have longer head stocks with 3 bearings, wider ways, quick change gear boxes, sometimes more HP and more substantial bases. The QMT 1440-HD is similarly priced as the 1440-GT and offers some good value for a Chinese made lathe.
The negatives for me on the 1440-GT at the time I was looking were the change gears for threading, the 7" bed width and the steel stand. Having now put several hundred hours of use on the lathe the concerns of rigidity for the work I do have been put to rest. I have done a lot of single point threading and for the most common imperial and metric threads only two gears are used and it only takes a few minutes to swap over.
The positives that eventually swayed my decision were, made in Taiwan, high quality bed castings, D1-5 spindle (IMHO a substantial improvement over the D1-4), 2" spindle bore (I would now go nuts not having this), the pull out chip tray, foot brake and QMT customer service.
There are some minor things that could be improved:
1. Move the access for the coolant pump/tray to the outside of the stand vs inside which can only be accessed from the back.
2. Re-design the chip tray coolant drain outlet location to allow more extension of the chip tray.
3. Move the cross slide gib to the spindle side so the lock screw can be accessible with a DRO scale installed flush.
4. Make the stand 4" taller. Even my 5'5" daughter thought it was too low before I raised it.
5. Make the motor mount similar to the 1340-GT for adjustibility & service.
6. Hinge the gear cover to make gear changes quicker. (not a big deal but when I do metric threads I find myself leaving the cover off because I will be changing back after I'm done threading)