I cannot give you a comparison between the 2 since I have only experience with the Aptus17 (and other Leaf backs).
On the Leaf back I can tell you what to expect. I have been using the 17 for several months now and am growing more pleased with it by the day. Before that I worked with other Leaf backs.
Yes, mine is of towards green which is truly annoying however more brands seem to have this problem. A friend of mine has had several Imacons and they were all of towards red. This is easily corrected since it is always the same correction.
On the software side, things are very doable even in greater number of files only just not in LC10. Capture in LC8 and process in ACR is very doable. I have sets of actions & droplets ready. After every shoot I set the raws the way I like, group the files for the actions I like to to use and start processing via the Image processor. This way I need about 1 hour of my time selecting, editing & adjusting for about 200 to 400 files. My machine is busy for about 2 hours.
When I only need to do several files and I want to get the most out of it, I process it through LC10 instead of ACR before run actions on it. These files I tend to process on a 1 by 1 basis through PS as well.
So there is the real caveat with Leaf backs. The Leaf software is practically useless when you need to process larger number of images. The real stable & fast version when shooting tethered of the Leaf version is the older V8 version. A software update that will resolve these issues (allegedly) has been under development for quite awhile now as is the Windows version. Sofar these versions are way over time.
The 17 can practically be used up to ISO200 however for 200 you need to really expose well and preferably to the right.
What I like about the 17 is that the files are big but not too big to be able to process in larger numbers. Another friend of mine is complaining about the size of the files coming from his CF39, according to him these are not for day to day use.
What I like also is the fact the back doesn't need a wake-up like the Phase. The Leaf can be used at any time, this is especially handy when used on bodies that do not provide contacts to the back (large format cameras and stuff like Truewides & Miniwides, etc.). The Phase as far as I know needs either a special cable (like the kapturegroup release cable) or you need to release the shutter twice (please any Phase owner correct me if I am wrong here).
I like the big display however it is virtually unusable outside.
What I dislike about the 17. You need to take the CF card out of the back when shooting tethered. The thing is of towards green. Sometimes on higher ISO when underexposing you see a magenta strip on the right side of the image. A piece of crap software for processing. The less than 30sec. exposure maximum.
I need to tell that I use my back a lot of the time on a Truewide where I really need the cropped sensor size to prevent vignetting. Upside of this setup is that the cropped sensor backs tend to be significantly cheaper as are the lenses that I use.
All in all, for the price I paid for the Aptus17, You get a truly compelling image quality with files that can stand some real abuse. However I have no doubt the Phase will deliver equal quality.