I think this is one of those situations where if you have to ask, you can't afford it. Getting a +1 stability bonus on LRMs is nice, but it is not likely to make the difference in getting a mech to maximum instability, which is pretty much necessary to really get the true benefit. So unless you've got money to burn, I would say no. However if you are planning on running an LRM boat and you see "+2" LRMs available in the store, that is an insta purchase if you are currently using anything less. You really do want an LRM35 LRM boat sporting +2 stability damage boosts on all it's LRMs. With that, you can start harvesting the big mechs you really want.
You reserve all your mechs till your LRM boat can fire. Then, with your LRM boat, you nail the mech you want to salvage to max out their instability. The next mech to fire should be one with heavy ballistic weapons or at least a PPC, the mech with the largest additional instability generating weapons. That will knock the target mech down. Follow with two free targeted shots from your other two mechs. Rinse and repeat as necessary.