Add a Subwoofer to my Vandersteen 1ce s or replace with Revel Concerta2 F36

" And am hoping that upgrading to the F36 is the smarter choice than adding a sub that would seamlessly integrate. Any thought would be appreciated. Thank you."

I wouldn't trade the 1's for a pair of F36's. I've heard them side by side and the Vandersteen is a better speaker. If you get a Vandersteen sub, you can plan on keeping it for a very long time. Its an extremely well thought out design and will work with just about any speaker. 

" I have a VPI Scout with Sound Smith Zephyr III Cartridge running into a Musical Fidelity v-LPS that runs into a NAD VISO 5 Receiver and back out to a pair of Vandersteen 1ce's. Since I recently bought the Zephyr III, it revealed some inadequacies, and I am in upgrade mode."

I don't know how many hours are on your new cart, but it will need to be broken in. The difference from new will be significant. However, looking at your system, your NAD is clearly the weak link. You're not hearing what the Model 1's are fully capable of. Its really not the speaker's fault that your system has a lack of dynamics and bass. If you put a better sounding, more powerful amp on the 1's, the change will be huge. The sub is a good idea, but you won't be so compelled to get one with a better amp in place. 

" Well, you're talking about making some major changes in both electronics and speakers. This seems unlikely to yield the best results."
If you don't change something in the system there won't be any results, good or bad.

" I'm a big fan of subwoofers. They offer advantages that no floor standing speaker can -- placement options. However, the Vandersteen subwoofer approach has several constraints. There are constraints on the electronics when using the Vandy system. There are placement constraints of the sub(s) when using the Vandy system. There are constraints on the bass performance of the main speakers when using the Vandy system. The Vandy sub design is specifically designed for Vandy speakers -- the constraints of using first order filters."

That's not even close to being true, and you know it. Show me where it says Vandersteen subs are specifically designed for Vandy speakers. The owners manual clearly states you can use the subs with a wide variety of products besides as well.

As for placement and first order concerns, its just the opposite. The real issue here is that you have an Ax to grind with Vandersteen. I've read some of your other posts where you were arguing with John from AC, and some of the others. You were trying to push your version of the facts, and got upset when you were proven wrong. Now, every time I see you comment on Vandersteen products, its always negative combines with false info.

I'm sure when you read this, you'll have no idea what I'm talking about.