Tom,
I have been using BER49 by Bergger, which is the same developer as Atomal49, repackaged as a Bergger product. I use it with Bergger's own Pancro400 film in particular.
I've been skeptical about trying the BER49 developer, because I figured that Bergger's statement that BER49 gives superior results with their film was likely hype more than factual. However, I decided last year to find out for myself and acquired a package of it. In an effort to be more scientific about making an assessment, back in October I did a test where I shot one image repeatedly on a roll of 120 film, using my Minolta Autocord (sharpest lens I have in 120 cameras), with every frame the exact same exposure.
I then cut the roll of film into four equal pieces and processed each piece in a different developer. I used D-76, Rodinal, BER49 and Pyro PMK. The most notable difference* to be seen was between the clip processed in BER49 (on the left side of the photo linked) and the Rodinal 1:25 (on the right). You can see how harsh the Rodinal grain effect is - a developer that claims to produce "superior acutance", but when compared to the BER49 sample on the left, its no sharper, and in fact, the impression of sharpness is degraded because of the coarse nature of the grain.
The BER49 negative on the left has softer grain (BER49 is a solvent type developer) but appears to have superior acutance because the rendering of the brighter values is significantly better, giving the impression of greater detail. For me, the BER49 negative renders many of the values in a much more realistic way, and the effect is a much more tactile image. The shape of the twigs and the leaf surfaces is much more delicate and nuanced, whereas in the Rodinal negative, the values are compromised by the hard grain effect. The BER49 negative tells you much more about the quality of light and the textures of the subject matter, where the Rodinal negative degrades these virtues.
I suggest you take a closer look at a larger version of this image to see more clearly what I am talking about:
https://c2.staticflickr.com/8/7906/33346601438_8135339d8a_o.jpg
*I should add that the D-76 negative was close to the Rodinal negative in terms of harsh grain and lack of subtlety in the higher values. The BER49 and PMK negs were very VERY similar in overall character.
You can see the full image here, to glean how much of a crop the comparison sample is:
https://c2.staticflickr.com/8/7819/33346811688_c4ae2e8f4e_o.jpg