Just my 2c. The S.E.s have been out for more than a year,I'm at work but I believe mine were upgraded between 2-2.5 years ago. Mine were green board Monos,literally everything inside the cases had to be replaced,so I believe it would cost you nearly double the original used cost to upgrade in the future. The A'Gon description sounds very similar to mine. Now,worth would depend a lot on what your priorities are and what other equipment they would be paired with. Be advised that the impedence will drop down to either 10k,or,18k,depending on who you ask. They become more neutral in sound after the change,IMHO. If you want more warmth than the standard Monos,you'll have to add it somewhere else,these amps will EXACTLY demonstrate what's upfield from them. That said,at $2400.00,I believe they're a fantastic value,depending on condition,warranty,etc. They'll not only run down to 1 ohm(as will most other Odyssey amps,I think),but will have vast reserves,do you need that power? Most tube pres might have a problem w/a 10k impedence,mine doesn't but you should be aware.
Good Luck.