I had been looking for a good price on a Prelude OC1 canoe ( http://www.esquif.com/2008/canot_en.php?id=29 ) for a while, but then I found a deal on a L'edge and jumped on it. The L'edge is a better boat for a person of my size, and I am happy with it.

If I have three good reasons for not doing something then I don't,  Looks like you have 3 good reasons.  If you're happy with the L'edge then I'd stick with it.  However if your heart just really aches for  the PreLude and you would be thinking about it forever if you didn't purchase it then go for it. 

I say only buy it if it's expand the quiver. But if you have a L'edge then chances are you won't paddle it that much. Considering your over the weight range of an already unstable boat, it's likely you won't enjoy the paddling experience. But if you want to get the boat so you can outfit it and have as a fun project, than go for it, but I'd say that once it's sea worthy it'll be a mere museum piece in the garage and not a practical craft considering the other boats that you already own.

The Prelude is a piece of whitewater history and should be appreciated for what it has done to the Open boating community, but then again so is a Dagger Ocoee, Probe, or other classic designs.

The question I ask myself when buying a new boat is "is this hull design uniquely different from the other boats I have in the quiver?" For instance I recently bought a Corsica S even though I already have a "longboat" (Dagger Outburst), but my justification with the Corsica was that the diference in volume and rocker profile (more of a creek design than playboat design) justified the purchase. Price doesn't hurt either.