Ballistics Report
Workmanship: 
Turtle Beach had the best Vortex 1 design with the Montego, which Aztech immediately copied with their PCI-338 card. Unlike many cheap clone Vortex 1 boards, the Montego was not a reference design, although many people (myself included) were fooled by the quick Aztech knock-off. The Montego II is a carbon copy of the Montego I, with the exception of the updated core chip, but that's a good thing.
Probably the most compelling reason to buy the Montego II is that you won't be settling for the Vortex 2 reference design or the "volume" MX300 design. It's the same chipset, granted, but you'll be getting a unique design from a company noted for its high-end audiophile products. For example, the Montego II can auto-mute unused inputs to reduce overall noise. It's not surprising, then, that this card is a bit less noisy than the MX300 with no signal, though you would have to listen at deafening volume to hear the difference.
Our OEM card doesn't have four-speaker output, but the retail version will include
a daughterboard connecting to the S/PDIF port, which will offer S/PDIF RCA out (RCA and optical input and output on the home studio version) in addition to that missing speaker output they owe OEM buyers. Okay, just kidding on the last part.
Software: 
Like I said: what software? The reference drivers work great, and frankly that's probably all anyone needs. But it does show a lack of effort on the part of Turtle Beach. Where's my killer demo to show off my new sound card, at the very least? But that's par for the course for OEM products, after all. The retail Montego II will include more bundled software. Personally, I'm hoping for another copy of Incoming! At an MSRP of $99 for the retail version, I wouldn't get your hopes up in this category.
Compatibility: 
You've got flawless A3D 1.x, A3D 2.x, Directsound 3D, and promised future driver support for Creative's EAX (which has yet to materialize from Aureal). As far as compatibility is concerned, you have all the API bases covered with a Vortex 2-based sound card. It is the 3dfx of sound: you'll just never have to worry about support, it's a given.
Price (OEM): 
Once the retail version appears, with the missing 4 speaker and RCA digital output and some sort of bundle, the MSRP of $99 will be in line with the competition. Since the OEM version was never intended to be sold this way, don't buy it. Wait for the retail Montego II, which should be available within a few weeks. The home studio version, with added hardware wavetable MIDI, optical digital outputs, and sequencing software, will have a MSRP of $299.
Technology: 
The comments I made in my MX300 review about programmable DSP chips vs. fixed function accelerators still apply here. There are advantages to both approaches, but for what it's worth, fixed-function chips dominate almost every sector of the computer market. It's generally cheaper and faster to go fixed-function-all modern 3D accelerator chips are fixed function, for example. The tradeoff is that the DSP on the Sound Blaster Live! can be software upgraded to perform more audio functions, but the Vortex 2 chip on the Montego 2 cannot.
Sound Technology: 
The heart of the Montego 2 is in the right place-it's an Aureal Vortex 2 chip. Aureal is unquestionably the leader in 3D sound technology at this point. There is no other sound chip on the market that does a better job of rendering 3D sound, whether you're using two speakers or four. However, I cannot guarantee that you will find 3D sound compelling; as with all things, your mileage may vary, and the acid test is to try it for yourself.