Furman Elite-20 PFi Versus Reference SPR-20i

Give Furman a call.  They publish a contact phone number on there site.

I seem to have pretty stable voltage coming in. I’ve seen my 20 year old Monster Power HTS5400 fluctuating between 117 & 122. But almost is always right at 120. 
I can get the SPR-20i for a ridiculously low price and want it because it does seem to be a higher end unit than the Elite PF20i. 
I just didn’t know if having the SPR provided the same kind of protection/filtering that the Elite PF-20i does even though it seems to have both. 

If money is no object, the SPR-20 adds voltage regulation.  Not something many need, but it is another feature, an expensive feature as it requires more iron due to the transformer.