Should I replace my NetGear router and two extenders with an Orbi RBK50?

I have a Netgear R6250 router along with a WN300 RP extender and an AC 1200 extender.  At the router, I get about 25-30 mps., but in the area most used I get about 10 mps.  My main concern is throughput over the whole area.  Whatever lag there may be between zones is less important.

My questions:

Will I get consistent performance throughout the Orbi's range?

Would that speed be signifcantly greater than what I'm getting now?

Does the Orbi replace the router and extenders?

Is there any reason to keep or use the router or extenders after getting the Orbi?