Suppressors are a great addition. However, there are many pieces of the puzzle to consider.
1) Concentric threaded barrel. If it's a Gen-2, probably not too much to worry about. A Gen-1 will need to be threaded by a competent machinist/gunsmith.
2) Suppressor model/brand. Most modern offerings are effective for the caliber specified. Where they start to outshine each other is in modularity, multi-caliber use and effectiveness, ease of maintenance, weight, and longevity.
3) Suppressor mounts. A "pistol" suppressor vs a "carbine" suppressor doesn't really mean anything except for how it mounts to the gun. Many semi-auto pistols (but not all) won't function reliably with a suppressor unless the suppressor has recoil-boosting device (sometimes called a Nielsen device) to assist. Consider the weight of the suppressor, hanging off the barrel, plus the fact that those internal baffles are acting like sails on a boat, pushing away from the shooter when they catch the muzzle blast. It all acts to counter the normal operation, so a recoil booster is needed to cancel it out. This spring assembly is fine for those pistols that need it, but if you mount that same setup on a fixed barrel, you'd be punishing the end of the rifle with every shot, hence the desirability for swapping out a fixed barrel spacer for the spring, or a completely new mount. If the suppressor can't adapt, then the use will be limited.
4) Ammunition stability. What you care about for suppressor use is that the bullet is spiraling nicely when it exits the barrel. No tumbling, or slow wobble. These things might cause the bullet to impact the suppressor (a "baffle strike") which on the one hand might just affect accuracy a bit, and on the worst case it would cause the bullet to careen off angle and blow another hole in the side of the suppressor. Before you shoot ANY new ammo through a suppressor (reloads OR factory), paper test it. Shoot it at a paper target as close to the gun as possible. If you have anything but clean holes punched, do NOT shoot that ammo/barrel combo with a suppressor. I've seen factory subsonic ammo boat tail on a target five feet away with the wrong twist-rate barrel.
5) Method of purchase. You can buy the suppressor as an individual, with a trust, or with an LLC/business. There are pros/cons to each. More than enough explanations elsewhere.
6) What will you want to use the suppressor for? This answer will help you prioritize the plethora of available options.
Personally, I've had great experiences with a Silencerco Octane 9 HD. Quiet. No noticeable "first round pop" (FRP), stainless steel baffles for ease of cleaning, and the unique baffle geometry (CTA) keeps the inner surface of the main tube build-up Free. Very modular assortment of mounts. Stable, well-known company with outstanding customer service in the rare instance you need it.
As for performance of a Gen-1 Sub-2000 in 9mm with a suppressor? Works great. Sounds great. Find good ammo that cycles well, and have fun.
