One of the things mentioned in the update documentation is that the REL instruments have a somewhat wider dynamic range than the standard instruments (as requested by a number of users). This is probably what you are noticing when you try to do a direct substitution. If you would regularly like to freely substitute between those types you may want to load the long bows file into the GigaStudio Instrument Editor, highlight the desired REL instrument in the instrument list, go to the \"response\" tab, and move the \"velocity response\" slider one notch to the right. It will then match the velocity response of the standard instruments. Do this with all the REL instruments you wish to change and then save the .gig file.
Actually, while you are there I\'d encourage you to experiment with different velocity curves to see how things work. You could then tailor dynamic ranges to suit your preferences. If you come up with some custom settings that you like save an articulation file so that you have a record of your settings if it ever becomes necessary to reload the original files. By applying the articulation files you can then retrieve your custom settings.
One small addendum: Whenever you are making global changes (like dynamic range) within an instrument be sure you have highlighted all regions, velocity layers, etc. so that the changes are applied to the entire instrument.