The answer is a resounding yes. I used some ideas from Dennis Clarke's burning snv_55b DVDs while watching for black helicopters to test the theory.

First I got the five parts from http://opensolaris.org/sxcr_dvd and stitched them together:

# cat sol-nv-b55b-x86-dvd-iso-a sol-nv-b55b-x86-dvd-iso-b \
sol-nv-b55b-x86-dvd-iso-c sol-nv-b55b-x86-dvd-iso-d \
sol-nv-b55b-x86-dvd-iso-e > os-b55b-dvd.iso

Then I determined if the checksums were correct:

# /opt/sfw/bin/gmd5sum os-b55b-dvd.iso
c6d968d1761ba20178bf1cbec3b61734  os-b55b-dvd.iso
# /opt/sfw/bin/gmd5sum ../b55b/solarisdvd.iso
c6d968d1761ba20178bf1cbec3b61734  ../b55b/solarisdvd.iso
# grep c6d968d1761ba20178bf1cbec3b61734 md5sum_x86.list
c6d968d1761ba20178bf1cbec3b61734  sol-nv-b55b-x86-dvd.iso

And then I searched for even a single bit of difference:

# cmp -l ../b55b/solarisdvd.iso os-b55b-dvd.iso 
# 

So they are the same bits. I can now use either image to construct the necessary ISO for the Connectathon build machines.

By the way, the Solaris Studio 11 is now included on the x86 DVD but not the sparc one.