I didn't think the bi-stem design was used so much for the retrieval as
for the ability to launch in a tight (size) STS envelope.  This is my own 
guess, based on similar designs flown on other large STS-launched s/c 
(GRO, UARS).  Also, there _might_ be some consideration given to mass 
requirements (bi-stems weight less than conventional S/A).  Finally, 
the HST arrays _do_ have the ability to be detached--remember, they're 
going to be replaced with new arrays.

However, as an ACS guy who's seen his branch management pull their
collective hair out over HST, I would voice a hearty 'yea' to using
conventional arrays over bi-stems, whenever possible.  No half hertz
flexible modes, no thermal snap, no problem.