I've finished replacing trees with AG trees, in the version of farmstrips wot I wrote specifically for FSX.
Please read the ReadMe, from which you will see that instead of modifying any existing version you may have, it's less fraught to scrap it and replace with the version in the download.
I think FT's initial impression coincides with my own, that the AG not only helps framerates but improves the look of the scenery.
If you have any problems installing the AG files to an orthodox Horizon setup, dare I suggest that since he's managed to do it, FT's your man.
Having lit blue touch paper he retires, hastily. Download available from: http://www.homepages.mcb.net/gwinsk/FARMS%20FSX%20WITH%20AG.zip Gerry Winskill