I've been listening very recently to the violin sonata, cello sonata
and string quartet in the Timpani recordings (and there have been several
recordings of the piano quintet, by the way!) All four of these works have
been extremely high on my personal list almost ever since I first heard
them.  Most exist in other recordings (the cello sonata in a recording with
the sonatas by Lalo and Magnard, for instance- the first one I heard of any
of those) as well but I personally think very well of the Timpani set,
which also includes some fine works for harp, viola, oboe, etc.  ...

The violin sonata, with its propulsive opening theme, memorable second
subject, fine intermezzo, and the powerful slow introduction preceding its
finale (not to slight the slow movement!) and piano quintet which needs
no praise from me- especially I should like to see performed in more live
concerts, and the very fine and memorable cello sonata as well...  though
hearing the string quartet again recently reminded me how much I enjoyed
that, too.  As with several other composers best-known for their output in
a less-traveled medium (Rheinberger, too, again organ with him and again a
composer who excelled- I believe- in the chamber realm- the string quintet
and piano trios being my favorite examples in his case) Vierne was a
composer the scope of whose output has taken time to be recognized, I do
think.

(Widor is a case I'm somewhat ambivalent about- his organ solo symphonies
are quite fine; I am less impressed by the first of his symphonies for
orchestra (in F- I have not yet heard no. 2 in A), somewhat moreso by such
chamber music as I've heard.  Jongen fares better, I think, in what I've
heard so far (I'd still like to hear his string quartets, for instance, his
sonatas with solo instrument, and other works.  But he's also more and more
widely-recorded than some mostly-organ composers I might mention.)

Eric Schissel
http://www.lightlink.com/schissel
http://malver.livejournal.com