I’ve not ridden a JJ, but did own a Wolfhound which had near identical geo.
That was a heavy steel frame and also very stiff with a unicrown fork.
I would say it was stiff to the point of unforgiving and heavy to the point of feeling slow
I used it through two winters, plus a few times through the year, but could not get on with it in the faster drier conditions
I now ride a ti Kona Raijin with a Niner RDO CF fork and that is totally different
I got the bike last Autumn and have ridden it ever since. I prefer it to my other 3 bikes.
Compared, it is more lively, more comfortable and I can get into a flow more easily
The WH was difficult to hold a line when pushing on, and you really felt everything. In the more plodding Winter it seemed to fit in nicely
This is not a better/worse, the Kona is the only other rigid bike I have ridden to compare with