Aromatic vs Dry Hop

Instead of dry hopping (and a secondary) can you just add it to your late addition (instead of say .5 oz of X hop @ 5 mins and also for dry hop just add 1 oz) for something like an IPA?

You can add hops at flamout or last few minutes for aroma.Dry hopping is favored as far as aroma intensity-as well as drinking them right after they have carbed for peak aroma.

How fast does a dry hop die out? If I drink my IPA stash in about 1.5 months is it worth it to dry hop?

Well it depends on the hops really you could get hops that are not as fresh as you would have liked,like i often encouter. IN generall though you would notice hop freshness with age.Ive dry hopped and been disapointed well before a month.Its really about hop age/storage. But some hops can age well ,which ones? i have no idea.It depends on the hops life also and how it was stored.

Dry hopping gives you a "bright" character to the aroma that late hopping will not give you. As others have said, how fast the dry hop character fades is hard to predict and control, but I've never heard anyone say that fact makes it not worth the trouble. As a stylistic nitpick, dry hopping is part of the distinct character if IPA, regardless of whether it's British or American, so I'd say if you're making a different style if you switch the hops from dry to late.

BTW, you can dry hop in your primary - just drop your hops in. Either loose or in a hop bag. If you use a hop bag, make sure they're loose, not packed tightly, and remember they will swell when they absorb beer.

Try a Hop Rocket. They work great and give tons of hop aroma.