Hi Bob,
First of all I only know a little about this but here goes:
The 3.3 has been around for a while and when it first came out, and for a while later, the CCD sensors on cameras were very small. Worked well back then, but I think that you would get a lot of vignetting with today's size sensors.
I have the GPS LX200 10" and almost always use the 6.3 reducer which is also meant to flatten a little as well and that works well. In the Meade 3.3/6.3 manual, it states that they both do some flattening so you may not want that with your ACF.
It's always nicer for a faster image though, and I can recommend the AstroPhysics - CCD Telecompressor(CCDT67). Same as focal reducer.
No flattening.
From their website
http://www.astro-physics.com/product...&%2027TVPH.pdf
But hey, if you have a 3.3 or can borrow one, then give it a go. Then you will know exactly how it works with your gear. I did that...once.
Cheers,
Damien.