Yes, the NH35 is 1.4mm thicker than the 9015, the 6L35 is thinner than the 9015. So that is the base the manufacturer starts with, then the case back, glass, bezel, all that adds up,depending on their design and purpose.
Both movements are not comparable, the NH35 equivalent in Miyota is a 8xxx series. The 9xxx is twice as expensive as the NH35.
The equivalent of the 9xxx series would be a Seiko 6L movement, but they are not as common. I agree with you Seiko could do better using that 6L movement more often.
I have two Miyota 9x, one in a Citizen and the other in a Wise diver. They are great in thinness and also 28800 bph and accuracy. It's great Miyota is offering this movements so microbrands can use them at competitive prices like their GMT.
When the crown is pull to the first position, the seconds hand moves to point to the current timezone displayed as one of the cities in the bezel, then turning the crown moves the seconds hand to select the desired timezone and the hour hand, minute hand and date will move to display the correct time there. Pushing the crown back to normal position makes the seconds hand to move along the dial until it displays the correct seconds again. It's pretty cool to see and play with it!
Where I live it is very hard to get the time signal regularly unless I leave the watch out of the watchbox for the night and use the little Citizen antenna to improve the reception.
On its own, the movement drifts about +6-7 sec per month, not bad, but my Citizen Promaster with the E210 movement is more accurate.
While not as accurate, the little brother of the Chronomaster has some tricks up its sleeve: radio-controlled and world-time, on top of the perpetual calendar.
This account is verified. WatchCrunch has confirmed that this account is the authentic presence for this person or brand.