This is why I allow Regain Guard to proc the Retaliate reaction. This gives the Dagger wielding attacker an opportunity to oppose the Regain Guard action by making an attack roll.
This means that “against an enemy who doesn’t want to give you space to maneuver with your now inefficient long weapon” it is " extremely difficult to step back enough in order to make the pike effective again".
So, Alice is armed with a Dagger and Bob is armed with a Pike.
Alice attacks Bob and Break’s Guard vs Bob; Bob loses Guard.
Bob declares Regain Guard as a Minor Action.
Alice declares Retaliate as a Reaction. Paying 1 Heat.
This is resolved as a Struggle with, all other things being equal, Alice’s D1 Melee test with +3d20 vs Bob’s D1 Parry Test. If Alice succeeds, then she’ll deal damage as normal and if Bob succeeds then he’ll have successfully regained Guard and be able to attack from relative safety.
A Struggle vs D1 5d20 is enough to make me strongly consider dropping the Pike (Free Action), drawing my Shortsword (Minor Action) and just attacking in the clinch (Reach 1 vs Reach 1, so provided it’s 1v1 Guard is irrelevent).
OTOH vs an enemy who doesn’t try to stop you (ie one who doesn’t make a Reaction) it is very easy to Regain Guard. That feels right to me.
See this thread for the previous discussion.