Here is the 715 out of the camera shot, using my in-camera WB1 set for the 715 conversion:
Here is the same shot except I added the 87C filter. I did set an in-camera WB2 for it and used it here:
Note that it the shakes on the building roof across the street are painted a barn red, which you can detect on a good monitor in this web jpeg. It is a very overcast day here, so no direct sun but some brightness from it. Both images were processed "as-shot" in C1 except for my standard identical raw conversion settings tuned to for the GF1 IR camera. (In point of fact, I would tweak them a bit for the GF1 with the 87C going forward, mostly in the form of some additional capture sharpening.) The main thing I note other than the fairly pure and neutral monochrome tone in the 87C shot, is the evergreen vegetation in the background went a lot more white. At 100% pixel view, the 87C shot also exhibits slightly more IR veiling. The exposures were f6.3 ISO 400, the 715 bare camera was 1/800th while the 87c dropped to 1/250th, or 1-2/3 stops less.
Finally, in CS with the 87C raw converted out to a 16-bit Prophoto tiff, you can read some slight color as you drag the dropper across the image. The RGB values are all within maybe 2 to 3 point maximum spread thoughout, and when you convert to sRGB the image becomes a very nearly pure, and perfectly neutral gray monochrome -- note that I did NOT desaturate or convert the 87C image to grayscale, it is shown as-shot save for raw and web jpeg conversion.
Honestly, I couldn't be happier -- I now have the best of both worlds for IR with just a simple filter addition!
PS: FWIW, I use a "HeavyStar" W46 metal lens hood on my 20/1.7 lens. The nifty thing here is that HeavyStar cuts standard filter threads for the light baffles on the insides of their hoods, and in the case of the W46 that thread size happens to 52mm -- or identical to the filter thread on the 14-45 kit lens, so my 52mm 87C filter can be easily mounted on either lens.