Update: Ok, I bothered to spend 1 hour to test Paragon leveling after someone came out with a revised experience table. Without even running an efficient build on my wizard, I ran Torment I (just to basically one shot stuff quickly), did the Act II Oasis over and over, and was able to get 150m XP over that hour. That is without decent gear, no experience bonus items, not hitting any experience shrines, nor doing that run efficiently.
Looking at this updated table, up to Paragon 100 (for Paragon 2.0), that rate of experience is basically around 1 Paragon level per hour. Thus running bounties and/or rifts with XP bonus items, co-op, finding Pool of Reflections, and running on the highest difficulty where you can mow down stuff quickly, it’s possible to average 2.5-3 times this amount easily. Basically (with this experience curve which can still be subject to change), someone with zero Paragon can basically get to 100 in around 75-100 hours by just playing the game normally without doing mind numbing grinding.
Also, the Paragon experience requirements at lower levels is much higher. Previously, getting to Paragon 2 required just 15,840,000 total experience; with this updated curve, it now requires 131,580,000 total experience. This is why many folks who have cumulative Paragon experience below the requirement for P100 in Paragon 1.0, are seeing their Paragon level reduced in the PTR/closed beta.
True, while this initially means a loss in Paragon points one can use at the start, this is offset by how quickly one can now Paragon level. And as one surpasses P100 (in Paragon 2.0), leveling is still happening at this hourly rate until P200. And even after that, the rate is still less than 1.5 hours which is pretty decent. Thus it’s best to just disregard current Paragon level (if playing on live) and just focus on the total experience.
As the note in the spreadsheet says, there is still an incentive to Paragon level on live if that hero is close to 65. Again, it’s about how much experience an hour one can get; thus this is especially true if you can exceed 150m XP/hour (which means MP10 co-op crypt runs since many of those cumulative runs can average around 240m XP/hour). That kind of grind/playing is personally not for me though. On live, I don’t even come close to 80m XP/hour as the highest I can solo efficiency (using perma-archon) is MP7. So for myself, even though my actual converted Paragon level on softcore will drop from 100 to around 67 , I can actually level back to that much faster soloing with 2.0.1/expansion, than trying to gain the equivalent experience soloing on live now (plus I cannot stand playing perma-archon for long periods of time; but it’s the most efficient way). As for hardcore, I’m putting that on the backburner in the beginning.
Update 2: The above is in error. One’s shared paragon level will never be lower than ones current highest level Paragon character. Plus someone with just 1 Paragon 100, will be P113 in the new patch. This is a posting from Lylirra about an unintended effect when copying over characters to the current patch (which has since been hotfixed). Thus the above calculations, may not be totally accurate.