@emery02, NB or CSS does matter, as this would have implication on whether you could qualify for FHSS. NB also makes LBT usable (remember LTE-U does use LBT for Wi-Fi coexistence). Therefore, duty cycle limitation does NOT necessarily apply in EU.
Synchronization is a sensible thing to do very obviously, and from the little I know about Symphony Link it seems a good patch to LoraWAN. The slight overhead it carries would be long forgotten once the density of end devices really picks up. This overhead also decrease when increasing the density of base station.
It was clear very early that LPWAN would not be about sheer range, but it is, like always in wireless communication, all about capacity, interference management and spectrum efficiency.
To your point, Lora CSS does have slightly better sensitivity than regular FSK at a given datarate. This is not so true if you compare to other standard physical layers like 802.15.4g OQPSK (-126dBm@6.25kbps) or its NB extension like Weightless-P (-136dBm@625bps).