Yeah, I would say that you can feel free to use the LSDAS service. My one exception is Stanford, which encourages its own form and is my first choice.
http://www.law.stanford.edu/admissions/jd/procedure.html"You should be aware that this service [LSDAS] will not accommodate any letters written on your behalf in which your recommender describes your qualifications specifically for Stanford Law School. Rather, these school-specific letters must be sent directly to us by using our Statement of Instructor (Form C). While it is your decision whether to utilize this service, please be aware of the high value Stanford places on school-specific letters of recommendation on Form C."Again, I'm following along because it's Stanford. For the rest, they can enjoy my LSDAS letters (if Yale wanted a special one, I would probably give them one too though).
Actually, with the new rec forms, you can send school specific recs. The downside would be that the school specific form wouldn't be attached, unless the recommender incorporated it somehow with their rec. Not saying any way is better, but I am glad that all the schools I'm applying to prefer or have no preference as to which rec form to use!