Distance and defense: Tiny tweak for GURPS combat

Here's a minor, yet-untested melee idea that came up during chatter over some GURPS combat scenarios:

Closing a distance gap to attack gives the defender more time to react than starting out close enough to strike. Game that with this simple rule:

• If the attacker needs to Step or Move to get within striking Reach, the defender gains +2 on Active Defense.
• If the attacker begins his turn within striking Reach (even if he chooses to Step or Move anyway), there is no mod to Active Defense.
• If the attacker begins his turn and strikes in close combat, the defender takes -2 on Active Defense. 

The first case represents having to first move to get within striking distance, handing the defender extra time (as well as an extra, clearly visible indicator that the attack is coming). 

The second case above is the default combat norm: You're already within range to strike, and you do so. Nothing special going on.

The third case helps model the "roaring and punching" aspect of close-combat free-for-all. Attacks come from so close, and thus come so fast, that it's hard to defend against them (or even see them coming in the first place).

All extremely simple to play out when using a hex map. How will it change combat? I expect the following:

• There'll be more circling and probing before the clash. When two fighters face each other just outside of reach, the first to close the gap and attack is at a disadvantage: The recipient of the attack gets a +2 on defense, while (unless the defender retreated out of range again) the initial attacker gets no such bonus when the initial target returns the attack.
• The fighter with the gumption to attack first has more need than ever to Evaluate and Feint before attacking, to overcome the defense bonus. The fighter willing to receive the first blow (to get that +2 AD), on the other hand, can really boost defenses by choosing All Out Defense (even without Retreat). More difficulty in making that first attack + more benefit to picking AoD and receiving the first attack = more "You go first!" circling.
• Close combat fighters, no longer able to parry and dodge as nimbly as they can at arm's length, gain incentive to throw away defense completely and go nuts with All Out Attack. Which, I've always thought, is how close combat should play! 
• Similarly, a fighter stymied by his foe's expert parrying or dodging gains new incentive to forget the swordplay and just jump the guy, dagger in hand.
• Retreating remains tactically desirable in many, many cases – yet it now comes with a minor drawback as well. If your Retreat takes you outside your strike Reach, you'll have to Step to return the attack, handing your foe a defense bonus. Whether to give ground or stand fast becomes a more difficult decision. 

All in all, it sounds like a nice package of fresh tactical considerations, with no GM burden beyond the usual totting of really simple bonuses and penalties. I'll have to test this one soon!

Any thoughts or similar play experiences on your side, dear Reader?