'The value to your collection' is a very arbitrary and personal thing and is something you will have to decide for yourself. As for ripping open sets you bought for investment... I find it's best to decide whether a set is for investment or personal use before you buy. Be comfortable with that decision before you get your wallet out or you will always end up with this conflict. I don't even see my investment sets as Lego sets. To me they are just boxes with a monetary value. If you want to buy a set to build then do that, and always open it (and the bags) before it goes EOL, even if you're not going to build it right away. That way if you want to get more MISB sets for investment you still have time to do that and won't have the conflict of opening a valuable post-EOL set. I'm not sure if you mean your collection is MISB sets or sets you've built. If it's MISB sets, then that is an investment however you look at it. You've put money into it and it has a monetary value. Otherwise it's just a bunch of pretty boxes. If it's a collection of built sets, then don't wait until a set is EOL before you decide you want one to build. I think this is where your problem is. If you are waiting for prices to rise and looking to sell, then you are an investor, and those sets are investments. You need to keep your collecting and investing separate. Or at least, approach them as separate things.