Leaving a modern recurve strung over a long period of time will eventually weaken the limbs. If the bow is left strung in a hot room it could cause further damage to the laminations.
I have shot recurve bows since I was 10 (am 51 now) and built recurves for about 5 years. I have built wood laminated and single piece wood bows as well. The old feelings were that the bow would take a "set" are not really true with ANY modern recurve, but they will eventually weaken buy a few pounds draw weight. Plus, depending on how you store it you could damage a limb that way.
The Black Widow bows are made the same as any other modern recurve, I've seen their factory and production, but as a general rule it is best left unstrung.
As mentioned before, do NOT unstring it without a proper bow stringer. Do not use the step through method.
If you are on a 2 or 3 day hunt, don't have your stringer, you are far better off leaving it strung and just lying flat. The fiberglass (or carbon fiber) in the limbs is actually what holds the shape of the limb, but the wood laminations can alter this if severely stressed, like being twisted.
Twisted limbs can be repaired about 50% of the time. If your bow limbs look like they are not in alignment when strung, they may be twisted, and if that were the case, leave it and walk away.
Otherwise like GB said, you used to own the bow, and if the friend hasn't twisted the limbs, you know how it shoots. A bow you shoot well is worth whatever you are willing to pay, no matter what the brand name or model is.
