With a 2" spring spacer, you'd have less rebound but the same amount of compression. So, if you're NOT going to do any off roading harder than the stock suspension can handle, I'd think you'd be fine.
Yea, maybe suspension parts would start to wear out around 150k miles instead of 200k miles. We're talking tie-rods, ball joints, shocks, etc.
Like I said, my biggest worry is the bump stops, if the lift kit takes those into account. If you bottom out your suspension, the suspension pieces hit a hard rubber bump stop before it compresses enough to damage the spring, shocks, bushings or other parts. So with spring spacers its possible you'll hit the end of travel for the shock, bushings or spring before you hit the bump stop and damage those parts.
So, the kit has to do one of three things.
1.) Include bump stop modifications, like a spacer for the bump stop or an extended bump stop.
2.) The suspension already has enough travel and margin that putting a spacer in it still hits the bump stop before it hits the end of travel for the other suspension parts.
3.) It defeats the bump stops and doesn't do anything to protect the suspension.
If no 3. is the case, yea, the spring spacer kit is likely to ruin your suspension, at least break parts that can be easily replaced (but still cost money and time to replace). That is assuming you're drive it hard enough to bottom out the suspension once in a while, but lets it put it this way, even a little old lady that only drives to church on Sunday still hits a pot hole or speed bump every once in a while and bottoms out the suspension. Well if she drove a commander to church, that speed bump or pot hill might NOT bottom out the suspension, but you already said you want to drive some mild trails, even mild trails you might encounter some stuff that would bottom out the suspension. So, look at the parts or literature from the manufacturer, even email them that question about bump stops, before buying.
Last edited by Mongo; 11-21-2013 at 10:01 PM.