Shouldn't be a problem with either dwarfs or discus.
Farlowellas are one of the larger gentle loricids and will not eat plants or get themselves into trouble with tankmates. They can also take reasonably high temperatures - their natural habitat includes weedy riversides in amazonia that may heat up more than the mainstream currents around them.
We have aprox. six farlowellas in stock now. I picked them out myself because they were different than the usual imported species... this one is more highly mottled, with a thicker, spiny, reticulated rostrum.
A 37 gallon tank could easily hold three or more twig cats.
-Sam