Have you been in a situation where you have one front tire spinning and the other is firmly planted on the ground? Were both rear tires spinning preventing you from making forward progress? I have been using my 4x4 for about 13 years and have 'needed' a front locker for a total of less than 200 yards. Locking the front end will greatly increase steering effort and also HUGELY(!) increase the turning radius of you truck (only when engaged)
It's is your money and you are certainly free to spend it as you wish but I think the $1500 would be better spent elsewhere.
REX