Sent you a PM.
It eliminates a possible clutch pulley & bearing failure device along with eliminating coolant leaking from the unit. Also removes a HP drag on the engine when the clutch is engaged.
And, the viscous heater is no longer available new by Mopar, it has been discontinued, so the only replacement option is finding a good used unit if it fails. The Viscous Heater does not provide a lot of actual heat input into the cabin heater.
I have sold kits to some customers in the northern states and a few in Canada and so far none have complained of having cabin heat issues.
I reside in the south where the lowest temps we see in winter is in the teens and having NO Viscous Heater has never caused any cabin heat issues. My Jeep's heater heats up very quickly within a mile or two of driving.
Maybe some of those owners in cold climates can respond to your question as they certainly can speak better on the subject than I.
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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve