Zoot45,
I can only add a couple of comments. You really need to figure out yourself, what you want different in a speaker. Certainly things have changed, that doesn't mean you have to. If you can say, I really want more detail or I really want a better sound stage or midrandge is too recessed or too forward, top end isn't smooth, you can then get firm recommendations. Otherwise "can you get better speakers today for $2000?" the answer is clearly yes, but will they make the difference of what you are after? Only you can answer that. I don't know where you live, but my guess is that some audiophiles out there would let you visit and make comparisons with your Celestions. If you don't know what you want differently, you need to listen for yourself and decide what you would like to hear differently. Everyone here could then chime in with clear examples of how different speakers sound differently from your SL700SE
I can only add a couple of comments. You really need to figure out yourself, what you want different in a speaker. Certainly things have changed, that doesn't mean you have to. If you can say, I really want more detail or I really want a better sound stage or midrandge is too recessed or too forward, top end isn't smooth, you can then get firm recommendations. Otherwise "can you get better speakers today for $2000?" the answer is clearly yes, but will they make the difference of what you are after? Only you can answer that. I don't know where you live, but my guess is that some audiophiles out there would let you visit and make comparisons with your Celestions. If you don't know what you want differently, you need to listen for yourself and decide what you would like to hear differently. Everyone here could then chime in with clear examples of how different speakers sound differently from your SL700SE