ordered the pro mini shields and I'm not disappointed :) As small as you can get:

@rollercontainer the plug-in works fine with 2.0. You dont have to change the protocol value in the plug-in.

Oitzu and I (testing :P) are currently working on the Attiny support. To test you can download this library (the same as the original one except that it includes the attiny).

Its working so far.

Bugs:
Your node id is the same as child id (if you set a different child id, somehow the attiny ignores it and makes it the same as your node id).
Sleep is working with interrupt but it does the setup again after wake.
Sleep / timer is not yet working.

library: https://github.com/Oitzu/Arduino/tree/master/libraries/MySensors (You can replace it with your existing mysensors library)
example sketch thats working: http://pastebin.com/xRu2JNQ9

wiring:

                  +-\/-+
                 1|o   |8  VCC/CE  RED/ORANGE
 YELLOW  CSN     2|    |7  SCK     GREEN
 -       SENSOR  3|    |6  MOSI    BLUE
BLACK    GND     4|    |5  MISO    VIOLET
                  +----+

I'm using the normal NRFs right now, also on the gateway. But sometimes it can't receive some sensors (95/100 times its going fine).

If i use a NRF LNA PA will it receive also better? Or does it only matter for sending?

@tbowmo Got it! thanks. Stupid me. There was some lost soldering in the header.

@Yveaux the pirs work fine if you only have interrupts with CHANGE. I don't use a sleep timer. If you wake it up every minute or so its unreliable yes. but only with interrupts from the pir it works fine. I have 10 pirs like this. Oldest one is from march 2015 and still running.