Should I revert to Adobe RGB in both Lr and Ps to match the space that the profiles were built from? Or can I with impunity continue on my merry way - reflecting my delight with the new profiles?
I'm not sure how a printer profile can be "tied" to another profile in the way you describe.....the only exception to this would be if this profiling service you mentioned created a *device link* profile, a special type of profile and esoteric enough, at least for general photo printing, that it would surprise me if this were the case. (A device link profile is essentially a "hard-wired" transform between a source and destination profile(s). The profile conversion as well as the rendering intent are "baked in" to a single device link profile).
An easy way to test whether you're forced into using AdobeRGB as a source space is like this (you don't even need to print the image for this test):
* Take an image that's in AdobeRGB colorspace (for this test, you could simply assign AdobeRGB to any old image that has a good range of colors). Save this image, being sure to embed AdobeRGB. Call it "AdobeRGB.tif". Now, convert this image to the printer profile (use relative colorimetric w/o black point compensation). Save this under a different filename, being sure to embed the printer profile. Call it maybe "AdobeRGB_to_PrinterProfile.tif" or whatever.
* Go back and open the AdobeRGB image again and *convert* it to ProPhotoRGB using relative colorimetric w/o black point compensation. Save this image with a new filename ("ProPhotoRGB.tif"), being sure to embed ProPhotoRGB to the image. Now convert this image to the printer profile, again using relative colorimetric w/o BPC. Save this image with the printer profile embedded...call it "ProPhotoRGB_to_PrinterProfile.tif".
* View both of the images that you converted to the printer profile. If they look identical, you should be fine to use any source profile you want. If the profile is indeed tied to AdobeRGB in some way, the image that you converted to ProPhotoRGB and then to the printer profile should look very "dead" or desaturated. The reason is that, in the conversion from AdobeRGB to ProPhotoRGB, the RGB numbers in the file would've been reduced so they were properly "scaled" to maintain the same visual appearance of AdobeRGB in the much larger ProPhoto color space. Make sense? Also, using relative colorimetric w/o BPC during the conversion assures that the colors weren't mucked with in any way during the conversion, preserving the color appearance from AdobeRGB to the larger ProPhotoRGB space. (some pinhead (he sez with a smile) might point out that even if perceptual rendering were used for the conversion, it wouldn't have made any difference since these matrix working spaces only offer relative conversion tables anyway...which is true). :-)
Just to be sure that this is the case, you could go back to the AdobeRGB image and the converted-to-ProPhotoRGB image and print them using your printer profile (using relative colorimetric again...with a LUT-based printer profile it MATTERS this time). If the images look basically the same, you're good to go. If they look wildly different, then there's something going on with the printer profile they made for you.
Like I said, an output/printer profile should pretty much be indifferent as to what gets used as a source profile, the one exception being device link profiles.