Hi David @skyveyor,
Welcome back! I find a crashing drone a more “fun” way of losing money than stocks (probably cheaper too 
).
*I drafted a response last night but then got pulled away before finishing it:
The MN601-S 170kV motor was my leading option until a TMotor rep persuaded me to go with the V505 kV260. The main reason I went with V505 is to minimize air drag during forward flight with a smaller prop (16x5.4 vs. 20x6). There is the potential for cost and weight savings depending on the motor mount. TMotor offered to custom make a V505 integrated kit for me but the lead time did not work. The MN601 is slightly more efficient than the V505 and since you have a lower MTOW than I do (11.5kg), I think it is a good choice. Unfortunately, the MFE stock motor mounts will not fit the MN601-S (68.8mm diameter) as the MFE mount can only accommodate up to 60mm diameter motor. They will also not fit the TMotor FLAME or ALPHA 60A HV ESCs. If you go 3rd party route for motors, I would seriously consider the 601-X integrated kits since they include a motor mount/housing and all you have to do is put it on the carbon fiber tube.
As Ian @FIT-RS mentioned, I am unable to use PayPal for this project so I was forced to look at 3rd party options. Reliable components are a high priority since my sensor payload is not cheap. TMotor has a good reputation for parts as you know and my budget was able to accommodate (fortunately). It appears that the MFE motors could be quality parts and it’s possible that they come from the same factory making TMotor.
A simple quality test could be done with a 3 channel oscilloscope and a hand drill/drillpress to look at outputs of voltage amplitude and phase shift of the motor coils. A multimeter could be used in a pinch but you won’t get phase information, however, quality/condition of motors tend to be more obvious in the differences of voltage amplitudes (all other factors the same).
For VTOL and hovering I will be using V505-260kV, FLAME 60A HV ESC with a TMotor P17x5.8. For cruise I will be using an AT4130 kV230, AT 115A ESC with an APC 17x10WE prop. All propulsion parts are TMotor and the ESCs chosen are the recommendations from the TMotor rep.
Cheers,
Christian