Paradigm Studio 80 ver1, Upgrade to what next?

Looking for respectable suggestions as to what to upgrade to from my 1996 Paradigm Studio Reference 80 ver. 1 speakers. (I have already had to superglue the dustcaps on the 8" midranges and bass drivers as they have came partially off due to age). I am looking for a speaker that will show a outright dynamic difference with smoother midrange and midbass (and the speakers would be bi-wired). I am looking for a speaker with better transparency and resolution. I use only a 2 channel system and need the next speaker to produce the same or better sounding low end the 80's do. I would be looking to just drop in replace the speakers and not upgrade any other part of the system at this time due to budget constraints. I would be looking on the used market ONLY and the most I would spend after I sold my 80's to upgrade is between $1500-2000 (is this even a possible price range or does paradigm 80 ver1 a better value than most higher costing speakers?). Thank you for looking. I am up to any suggestions and that being upgrading to any other paradigm speakers (ie: 100's ver2) or such. Thanks
Version 2 of the Paradigm Studio range is a distinct improvement over Version 1 and the 100 is a distinct improvement over the 80. Further, if you contact Paradigm they will happily replace those drivers with the loose dustcaps.

Good luck. Let us know what you choose.

Thank you for the reply. I am still trying to decide and keep any additional inputs coming in.
I had the 80.1 for a while until I heard the 100.2 and now have them. I just love them to pieces even after comparing them to more expensive ones like the Vandersteen 2, PSB gold i, and B&W N804 in my own system (MIT cables, McIntosh separates, Sony ES player). I have done a lot of speaker swapping and am totally happy with the studio 100.2s - their excellent price is just a bonus in addition to the 3D imaging, huge soundstage, and pure smoothness. Arthur
Three speaker lines come to mind that would bring a step up in speaker quality, VMPS ribbon monitor series can be had within your 2000 dollar budget as well as Von Schweikert VR3.5 used and Silverline Sonata and Sonatina, used at about the budget you described. Either of those three lines would be an upgrade from Paradigm IMO.