They are doing exactly what you say but they provide two versions on their disk. A 32 bit version which has a 64 bit double presicion engine switch but also a 64 bit native version. It's not marketing fluff.
Here is all the data I could find to bring you guys up to speed. Throw all the darts you like.
SONAR 6 includes both a 32-bit version for Windows XP and a 64-bit version for use with Windows XP Professional x64 Edition. Experience 20-30% processing performance gains and access up to 128 GB of RAM on x64
Deliver productions at virtually any bit-depth, and sample rate (up to 64-bit, 500 kHz). Ensure pristine quality with POW-r dithering and Windowed Sinc sample rate conversion. Native 64-bit audio is the highest quality in the industry.
Mix with superior sonic clarity using SONAR’s industry-first, end-to-end, 64-bit double precision floating point mix engine (accessible on 32-bit computers).
Work natively with 64 bit audio, streaming 64 bit audio tracks end-to-end through your mixes.
SONAR 6 also features native support for 64-bit floating point audio files, allowing you to import, stream, and render tracks and mixes at the highest quality available in the industry.
SONAR In Review: Welcome to the World of 64-Bit Audio Engines
—Mix Magazine, September 2006
“As the first true 64-bit DAW, SONAR brings Windows users to the forefront of digital audio.”
“Listening to the 64-bit system proved to be satisfying and impressive. My mix had more detail and depth, and the image was better than when I played it on other DAWs.”
“I chalked this up to the extra dynamic headroom provided by the 64-bit system. The mix wasn’t as one-dimensional—rather, closer to what I usually encounter by summing through an analog desk. To be honest, it was the best that mix has ever sounded on a DAW.”
“The way I see it, the future of audio on a computer is here. The 64-bit leap is audible, improves performance and is the next logical step. Even if you remain in the 32-bit realm, you can still take advantage of the 64-bit mix engine.”
Why use multiple PCs when you can do it all in one? SONAR’s engine is optimized to take advantage of the latest multi-processor PCs and multi-core processors—including Intel®’s new Core2Duo. SONAR intelligently balances the processing load across all available resources guaranteeing you exceptional performance.
64-Bit Computing—Key Benefits for Musicians
SONAR 6 provides significant advantages to musicians when running Windows XP Professional x64 Edition on native 64-bit Intel or AMD processor-based workstations.
SONAR 6 experiences a significant processing performance increase which varies depending on your particular application. Benchmarks have shown improvements of 20-30%.
The increase in processing performance can result in more simultaneous tracks, realtime effects, and virtual instruments, along with closer to real-time latency for mixing and performance.
The x64 platform allows for access to up to 128 GB of RAM, an exponential increase from the 4 GB of RAM afforded by yesterday’s 32-bit computing platform.
The increase in system memory can result in the loading of larger, higher-quality sample content into RAM, increasing the amount of content capable of being used in any given project, while also reducing the latency introduced by disc streaming.
http://www.cakewalk.com/x64/default.asp - 64 bit resource page.