I keep seeing the same arguments made against RSL's, over and over. Many of them are just myths, word-of-mouth anecdotal stories passed down for so long that their original meaning has gotten lost. I figured I would list them here:
1. You should get stable before you open your reserve, and so you should disconnect your RSL.
First off, you should _not_ be stable face-to-earth when you open your reserve. The Racer manual spells this out explicitly - you should be head-high if possible to ensure a cleaner reserve deployment. Fortunately, you are head high the instant you cut away from your main, and that is the point at which an RSL will open your reserve.
Secondly, there are two universal truths in skydiving - you won't do it if you don't practice it, and you _will_ do what you trained to do. If you practice "cutting away and getting stable" you _will_ do that in the air, even if you someday cut away at 500 feet. If you do that, the only thing that will save your life will be your RSL.
Finally, before you decide that it's a good idea to cut away and then get stable, I'd recommend you do an intentional cutaway from a rapidly spinning canopy and see how long it takes. (Hint - it does not take just a second or two.)
2. You only need an RSL if you're going to forget to pull your reserve.
Rick Horn, one of the three people in the US who trains all AFF-JM's, once needed his RSL due to rig distortion. He could not find his reserve handle. If you are more current at cutaways than a man who teaches them every month, and have more jumps than him (6000?) that might be a valid point, but I think few people are.
3. If you cut away on the ground on a windy day and you have an RSL, your reserve will inflate.
Simply not true. Try it next time you need a repack - go outside in the wind and pull your reserve handle. The PC will come out, the freebag may fall on the ground - and that's it. Unless you have decided to jump in a hurricane, even 25kts of wind (way more than most people will jump in) won't inflate a reserve.
Of course, you can disconnect your RSL once under canopy to prevent the reserve from opening at all if you have to cut away on the ground. That's a convenience issue, not a safety one.
4. You can practice cutting away on the ground, so how hard can it be?
RSL's are not for normal cutaways. They are for madly spinning mals where you can barely see one of your handles. They are for mals while wearing a wingsuit, where you have fabric flying in your face and you can barely see. They are for cutaways at 600 feet when someone sets up a hook right into your canopy and destroys it. These are the situations where RSL's save lives.
If you will never be in such a situation, great. But I have discovered that those situations find you, rather than the other way around.
5. You have to "fall away" from your main to guarantee you won't entangle with it.
Simply untrue. I've watched an awful lot of rig testing, and the physics just doesn't let that happen. Even in a malfunctioning canopy, the forces work to separate the main and the jumper/reserve.
And if you postulate a bizarre scenario where the reserve PC can somehow entangle with the main? The reserve will simply open faster.
All that being said, there are still reasons not to use an RSL. We disconnected all our tandem RSL's a while back because there had been some problems with broken risers, and that's a risk when you use a one-sided RSL. If you're doing something bizarre (like jumping a 46 sq ft canopy and opening at 5000 feet) an RSL will probably not help you much, and if you're doing intentional cutaways or CRW, it makes sense to simplify your gear and be able to fall away from something before you open your reserve. But for a lot of people it makes sense.
Personally, I recommend everyone use one until they get to 200 jumps and/or have their first cutaway from a spinner. At that point they will have the experience to make a good judgement on their own.