I'll take a stab a this. I initally purchased the Vantage in February 2008 as a primer on ML. I had never owned a pair prior. Heard them, but could never afford them. Folks here were very helpful in teaching me how to get the most out of them. Positioning, room treatment, tilt and toe were my lessons. I added a sub because I thought the bottom was a bit thin in my room even with treatments. I was very pleased with the Vantage. The mids and highs were very close to what I was looking for. There was some detail that was hinted at but remained in the background, whispering to get out. I tried several sets of wires and ICs and settled on the Mapleshades as recommended by Gordon Gray. If the Vantage was the top of the line, I would have remained a happy camper.
I had heard the Vantage and the Summit side by side. I knew I wanted the Summit detail and presentation. I was prepared to upgrade to the Summit until I heard about the Spire. Same size panel and new cross over seemed to me to be cutting edge without the big jump in price to Summit. The loss of the second woofer did not concern me since I had the nice sub. I could not find anyplace to listen to the Spire without an expensive trip. There is not a lot of info on the Spire yet and bought them on somewhat blind faith. I've had the Spire for a bit over a month now and have not been disappointed. Some tweaking of positioning locked the speakers onto the room. The detail and stage is just stunning. The sub is collecting dust right now and it may be moved to the HT. Some may prefer that added umph down in sub land but I do not feel it is necessary for me. The bass is very defined and multi note capable. A kick drum sounds and feels like a kick drum. ML has not fixed that faintly audible woofer rumble, buzz or whatever you want to call it. It is not noticeable while playing music even at soft levels.
I'd like to say it was worth the cost to me. To you? Only you can make that call. 3K in room treatments, wires and other tweaks could make the Vantage a tough speaker to beat. On the other hand, 3K in room treatments, wires and the Spire is top notch in my book.
Gordon