HW95.
I have a Summit NP2 in .22, which is the same as the Trail NP2 you're considering, only the stock is different. Here's my analysis of it. (also see my YouTube videos on it, user Jeremy D:
- Trigger breaks cleanly, as advertised, but it is so heavy that it wrecks out-of-the-box accuracy.
- The trigger can be lightened up by replacing a spring, but it can only get down to around 2 lbs., due to the design of it. Go any lighter and it won't cock.
- Cheap stock. Mine's plastic, and hollow in the butt area, but the finish on the wood Trails is kind of ugly and the wood isn't that nice either.
+ Quiet, probably much quieter than an HW95. The shroud really works.
+ Affordable, esp. with the coupon code from here, ordering directly from Crosman
- Scope rails are often crooked. Mine is, but luckily the 4X scope has little enough magnification and a large enough range of adjustment that it's zero-able.
- Barrels aren't as good as Weihrauchs. They're OK for the price, but not world-class. My best group has been about an inch at 30 yards. That's perfectly usable accuracy for a lot of things, but more is better. The HW95 will shoot groups half that size. You likely won't be happy with it, coming from a Diana 34. (RWS is just the importer)
- Very hold-sensitive
+ Powerhouse piston. Mine shoots at 23 FPE. But they're known to lose power over time, despite Benjamin's claims to the contrary.
+ No spring torque
+ No damage from leaving them cocked for long periods, since there's no steel spring to take a set.
+ Not too pellet-picky, considering their power level.
HW95:
+ Great trigger
+ Great fit & finish
+ Great barrel
+ Great balance of power and shootability
- Expensive, compared to the NP2
- Not as smooth cocking and shooting cycles as the NP2
+ Gives pride of ownership not found in a Benjamin/Crosman
+ Resale value; it has some.
- No shroud included standard, but AoA may be able to hook you up with something
+ Nice wood stock, even the basic beech
+ Built for 10X the number of shot cycles as the NP2
- Weihrauch after-sale support is allegedly not that good, though you're a lot less likely to need it, too.
The only thing I would really question is why you're considering another rifle of the same power level as your Diana 34? From this standpoint, the NP2 makes more sense. ...but how about an HW30s or Beeman R7. That's a nice compliment to your D34. Something that is light and easy to shoot all day, and just as much fun, even though it hasn't really got hunting power levels. Imagine having the power of a multi-pump pneumatic at 10 pumps, but only having to "pump" it once. I've taken a couple squirrels with mine, but it takes a perfect brain hit. Chipmunks and pest birds smaller than crow are no problem.
...or even an entry level PCP in .22, and REALLY expand your horizons. A used Marauder would be sweet.