Some very good replies above though not everyone realizes that the GX suspension is not 4R suspension.

Anyway, if stock is not an option, then the BP51 seems as the winner for the intended use. Above, too, the BP51 seems to get the nod for street driving, as it should.

The BP 51 vs Icon 2.5 is not apples for apples.

The BP51 is 2.0 with internal bypass that acts soft presumably always in your intended use but will allow you to do just fine when you hit something hard by mistake. I am not able to quickly find the BP shaft size but I bet it is smaller than the 7/8s used on 2.5 shocks. Since you cannot push the otherwise stock GX so hard as to need more than what the ARB offers on the far end of travel, you have a shot at getting what you need from the ARB 100% of the time. Whether it is worth the money over stock is another question and really not an interesting one for most of us since that is your business.

BUT, not so with the Icon 2.5, which is a much more powerful shock. Even if you downgrade the Icon springs, you will have a stiffer setup than the BP51 that, as said earlier, the GX will never use as intended, leaving you basically with the wrong setup 100% of the time. So this is not merely a matter of money, but a technically wrong choice for the intended application from what I can tell.

As for adjusters, they are not magic. No, I have never had them but I have talked personally with the owner of Radflo and listened carefully to others with lots of experience. The adjusters are for fine tuning. They will never correct for having the wrong setup in the first place.

So in this case, it looks like BP51 should be in the running and Icon 2.5 should not be.

My 2c.