Carrier Infinity 96+ two stage- Q:heat exchanger warranty replacement or new furnace?

First post -

Carrier Infinity 58MVP 80K was confirmed by local Carrier contract with secondary heat exhanchanger failure right at end of 20yr warranty. (mfg date 4400) I am trying to determine which path to take and would like some advice.

Two options:

A) Warranty replacement would replace primary and secondary heat exchangers - I would pay $XX for labor. That said, unusually, I have some key spare parts including:

ECM blower motor
Inducer motor fan assembly - complete
Furnace controller board - 2 spares
spare ignitor
spare flame sensor
Tri-Delta pressure switch

I think only other major spare part I'm missing is a 2 stage White Rogers gas valve 36E55-203.

B) New Furnace - Carrier (through local HVAC contractor) would provide $XX (ie similar in $value I would pay for warranty replacement) Carrier Trade-in allowance toward a new installed furnace.

Advice needed:
The local HVAC techician is stressing the 'age and likely failure' of expensive components an recommending to go 'new', however, I am struggling with the decision since I can have the same 96% efficiency for the next 15-20 years for only the labor $$ of the warranty replacement.

I appreciate the advice/thoughts to help me through this decision.

Thanks

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