I haven't seen any comparisons of SubjectsPlus and LibGuides. I know
of two articles that compare SubjectsPlus to other open source
options:
Free and Open Source Options for Creating Database-Driven Subject Guides
http://journal.code4lib.org/articles/47
The long road towards subject guide 2.0
http://meredith.wolfwater.com/wordpress/index.php/2007/10/24/the-long-road-towards-subject-guide-20/
One fundamental difference between SubjectsPlus and LibGuides, is that
SubjectsPlus is free and open source, while LibGuides is fee-based and
closed-source. On a "philosophical" level, this distinction may or
may not matter to your library; me (and I'm biased), I prefer my
software open source. I think it's more in the spirit of libraries
and our mission/role in society. Plus I'm sick of just having to live
with the way proprietary software works.
Overall, I don't know enough about LibGuides to make any sort of nuts
and bolts comparison. And I'm probably not the right person to be
doing so, anyway.
Andrew