I think William and Hamid Drake have spent the last 10 years proving there is a place for groove and time playing in improvised music.
Even then it depends on who is front of them. If they are with a first rate soloist Like Brotzmann or Kidd Jordan, or even them as duo it is great.
The last time I saw them it was a with a pretty weak frontline and it was not great concert.
They are like a powerful engine and if the soloist has nowhere to go they will just get them there faster!
While you don't want to rule anything out, I think in general grooves are an ineficient use of the improvised music format, and are better served by pre-composed forms.
In the best case, each phrase by each musician should create it's own musical parameters, pulse and rhythm included.
I have heard that "heartbeat" spiel before too, it is kind of loose at best.
It is a bit like trying to find fugurative forms in a abstract painting as to way to understand it.
If the music was not created with pluse in mind it is purely conincidental.
http://www.emusic.com is a good deal has some great Parker albums on Aum Fidelity. they also carry the unheard music series, and the ESP catalog. which is a great way to get up to speed on the early history of improvised music.
Do a label search for "unheard" and "ESP". Those older recordings with two long tracks are only two downloads, like Globe Unity Orchestra or Manfred Schoof's European Echos.
