Exactly the way I look at it.
I'd rather 240rwkw than:
Standard RB25 or an average 26 that may need a rebuild and will need a new gearbox bolted up. Especially if you have proved to yourself that the RB20 you have has been reliable enough to start modifying.
People claim all sorts of shit when trying to sell motors... just rebuilt etc etc, only 100,000kms etc but then, why are they selling them? Of course, there may be some cases where receipts are shown and there is a genuine reason proof but you will find most of these will be out of the budget.
At the end of the day, I would love to havea 25 in mine but its just not financially viable for me to do it. I would much rather spend $5k on my existing motor that I've owned for a year and never had any drama (fuel pump & touch wood ) than risk buying something out of car you don't see running that may have some internal problem you would never know until you have spent the money on having someone install and hook it up..
Obviously some people could share some good experiences they've had, but you never know what you're gonna get and its always best to prepare for the worst.