We've Minimig, FPGA-Arcade and someday Natami. So yes, there are plenty similar options for far less money and... well, Amiga, not AtariST, wich is better itself like it was in the 80's

Why is there no Coldfire-based Amiga project underway, like the Firebee that the Atari ST folks have going?

The NatAmi team investigated the Coldfire project years ago and discarded it because it wasn't sufficiently compatible with the 68060.  That's why the NatAmi team is working on the N68050 softcore and the FPGArcade Replay board has a softcore also.

Still, the extended rez / colors on a 68000-based unit are pretty sweet:
 
http://www.youtube.com/watch?v=HURSMZg98ZE
 
 
 
bp

Although Natami is still viporware, it is the closest thing (probably better) we will get to firebee.
Most progress is keep quiet, but they do give glimpses into their work.
This picture below is taken from Rune Stensland with a Native Amiga Screen mode at H=2040 x W=1280 ?? (cant make it out).
It has 256 colors but following the thread they mention Natami is 24bit color (16 million), the screen mode software hasnt been written for it yet
Rune also says his Natami boots from a CF card into workbench in 2 seconds.

http://a5.sphotos.ak.fbcdn.net/hphotos-ak-snc7/425246_315601381825521_100001269864388_957079_2045499285_n.jpg
Threads:
http://www.natami.net/knowledge.php?b=6¬e=44420&x=0&z=q3T2Ea
http://www.natami.net/knowledge.php?b=6¬e=44526&order=&x=1

And not forgetting the Elbox Dragon!

/Straight face

Any...day...now...

Simple.
Because the Freescale Coldfire processor family is not completely compatible with the 68000.
Many instructions and addressing modes are not present are other operate differently then they do on the 68K.
These differences require software traps that limit the efficiency of the Coldfire while it tries to emulate a 68K.

That's why the Natami uses a real 68060 or an FPGA emulated 68K CPU.

Does anyone know? Have the Atari guys figured out how to make an efficient emulator, or are they taking the performance hit? Or does the Atari use fewer of the 68K instructions that aren't a part of the ColdFire?

(Serious questions - I know close to zero about the Atari)

@Matt_H

It is not 100% compatible. It looks like they are going to patch all software they run on that board.

http://www.atarimusic.net/component/content/article/37-fp-rokstories/66-atari-firebee-an-atari-coldfire-clone-built-for-music

Btw it seems they are very capable developers and there are more resources than in an Amiga community.

@Matt_H
It is not 100% compatible. It looks like they are going to patch all software they run on that board.

I have read that they patch binaries at run time before they start. It works well enough for 1 Atari compiler but not the other which generates many instructions that need patching. This type of patching would never be 100% on the Amiga because it is difficult to identify small amounts of data as code or data. It's also time consuming on startup. It looks like it's not possible to only trap instructions on the fly. Some problems would be rems/remu using the same encoding as divsl/divul and byte/word sized stack writes being padded to 4 byte alignment (68k is 2 byte alignment).

I think the Natami team made the right choice in going the fpga enhanced 68k with ColdFire route. The ColdFire has some useful additional instructions that increase speed and code density. The ColdFire dropped some powerful 68k instructions and addressing modes that hurt code density. A 68k plus ColdFire CPU will be more powerful than 68k or ColdFire alone with the best code density in the industry while allowing the majority of 68k and ColdFire programs to be used.