I haven't heard any of Aragon's amps, so I did a little search to see what might have been said before in the saloon and I'm afraid I still didn't come up with much. Even finding specs on the Aragon was hard, since Klipsch has discontinued the brand and the Aragon domain now hosts a duplicate of the Klipsch web site. I did turn up a review of the Stage One and 3005 and an info page for the 3005 , but no mention of a 3500.

The Aragon 3005 has more power than the 7500 (300W vs 200W at 8 ohms, or 500W vs 300W at 4 ohms), and your LSi25's are notoriously difficult to drive - to the point where I'd definitely recommend the 7500 over the 7125 when looking at Outlaw's line-up. Either amp will have a much easier time driving the LSi25 than that Yamaha receiver you have in your sig at the moment. I've been very pleased with my 7500's neutrality and soundstage (I've got a review of it in my sig, along with a 990 review), but I just don't know how much difference there might be between it and the used Aragon. There's also the fact that the 7500 will be new - complete with five year warranty - while the entire Aragon line has been dropped from Klipsch's line-up. All indications that Klipsch is doing right by Aragon owners and continuing to provide timely support, but it's still not quite as ideal a situation.

Let us know which way you decide to go!