Are ARC new amps much better than older models?

I am in the market looking for an amp to match my Von Schweikert 4.5's. I have been looking on this site at the many models available afrom ARC. I just saw that The Absolute Sound gives their current lower end model product of the year in the amplifier category. As a recovering vintage audio addict, it really is hard to believe that the new ARC products are that much superior to their older products. I realize that they must have new wrinkles to sell their new products, but are they really that much better? I used to think that the SP 10 was about as good as it gets in preamps. Have they really exceeded it? How about their amps from 5 or 10 or even 20 years ago. I know that parts have gotten better but when Western Electric transformers are still the standard, couldn't one just update an older ARC amp with the newest high resolution parts available. Even ARC will update their SP 3 for about $1000.00 to meet current specification preamps. I must admit that I am very jaded about the high end. This is why I started my new system with the 5 year old Von Scweikerts. I am sure the latest generation 4's are better in some ways, but today paying $2000.00 for this much sound quality seemed a better bet than spending about $6,000 for some fractional percentage of improvement. Would this philosphy also work for the ARC amps?