When I want to use Logic's sounds in Live, I use an IAC bus to send MIDI to Logic, and an audio interface with loopback to get the audio back into Live.
Do you mind posting a quick tutorial on how to do this? I prefer the sound of Logic's pianos and would really like to use them without taking the AIFs from the Logic folder and remapping everything to a sampler in Live.
Sure, here's a description. I wish I could post some pictures but I don't have a handy way to host the images at present.
In Audio/MIDI setup, open the MIDI Window, click on IAC Driver and create an IAC bus(es) if you don't have some already. I keep two hanging around for sending MIDI to Logic, that way I can use 32 channels of MIDI (32 Logic instruments) in case I'm doing something like string scoring with lots of parts. I'll describe how to do it with 16 channels (one IAC bus), and from there adding a second bus for additional channels is easy.
Open Live first, then Logic. That way neither is rewired to the other. In Live, create a MIDI track and route its output to the IAC bus on some channel. Create an audio track whose input is coming from the soundcard input that you're using for loopback. (The soundcard will send one of its outputs to this input, that's the loopback.) Set it to monitor ON for now so you can hear what's coming out of Logic.
The Logic side is a little more complicated.
First you need to create 16 instruments in the environment, each one listening to a different channel on the IAC bus. First create 16 software instrument tracks in the arrangement view. Then go the mixer window in the environment and lay them out them to your liking. Set their outputs to the soundcard output you're using for loopback.
Now you have to make each of these instruments listen to a different MIDI channel. In the Clicks & Ports window of the environment, find the IAC bus at the top right of the Physical Input object. Create a Channel Splitter (New > Channel Splitter) and connect the IAC bus to the input of the splitter. Now Option-Click each of the 16 output ports on the Channel Splitter, and you'll see a destination menu; go to Software Instruments and select one of the 16 software instruments you created above. When you're done, each output of the Channel Splitter should go to a different software instrument.
That's it, basically. You can save this as a template in Logic and create new instrument "racks" quickly this way. I added another layer to mine, namely, I send each instrument output to a bus/aux and create an audio track in the arrangement for that aux. This way I can record all 16 instruments' outputs at once in Logic and export the files as a bunch into Live. Usually I don't do this however, I simply print the audio one instrument at a time in Live or don't bother printing it at all, just mix directly with the software instruments in place.