G'day Rob.
I haven't owned a Diana, but from all accounts they are supposed to be a good quality brand.
I do own a Winerack HW97K in .22 and would love to add a .177 HW77 to the safe. No go yet... the missus is still under the delusion I already own enough guns.
If you are going to be shooting rabbits reasonably regularly, then see if you can get your hands on a decent PCP.
However, as far as the ".22 for fur, .177 for feathers"
rubbish debate, either will work fine. Make sure you use good quality pellets, eg. H&N, JSB etc, but ultimately, It comes down to shot placement. With an air rifle head shots are king. Rabbit skulls (and foxes) are very fragile. It only takes about about 4 ft lb of energy in the brain pan to kill a rabbit.
Plenty of good air rifle hunting YT channels that use both. It comes down to ballistics, depending on the range you want to shoot, wind etc as to which calibre/weight gives you the accuracy and retains energy at POI.
PCP's are arguably easier to shoot (no recoil), but need all the associated accessories. Pump, tank, compressor etc...
Springers are a bit more of a challenge to shoot, but fun as no accessories required.
Just don't fall into the "maximum power!!" b@#$hit. Keep the velocity under say 950fps and a good brand air rifle will probably be a tack driver.
Hope this helps.
Plenty of good advice from knowledgeable people (maybe not me
![Rolling Eyes :roll:](./images/smilies/icon_rolleyes.gif)
) so if you're not sure about something jump on and ask.