No I will no doubt hear cries of foul at suggestions to make SH better, but of in my opinion anything that gives a HE player a tactical headache is a good thing. After all, noone wants to see WS5 2A Dragon Princes on the battlefield every time!

Suggested improvements directions:

Swift Riders
Silver Helms options in previous incarnations allowed them to perform the role of passable medium cavalry, with a good charge move of 18", better than almost all non-fliers in the game.
Swapping round the shield vs. Barding choice would accomplish this, make shields compulsory and barding optional, and all at the same points costs. This requires an errata publishing, no more.

Death or Glory!
Silver Helms are the proud scions of nobility, and all are eager to seek their own personal glory against the foes of Ulthuan.
Added wording...
Silver Helms led by a High Helm may add d3" to their charge and march moves.
This represents the High Helm seeking the glory of striking the enemy first, and the other knights eager to emulate their leader, and can also be fluff-justified by the fact that the Silver Helms reached Tyrion just after Malhandir at the battle of Finuval plain.
It also adds an element of "gamble" to Silver Helms units, as this then means that they are unpredicatble at the extreme of their charge range, denying an addition 3" to the enemy. It also could be the difference between a successful stand-and-shoot or not.

High Helm
Silver Helms are the proud scions of nobility, who will always be led to battle by a warrior of considerable prowess.
A Silver Helms units numbering 10? or more (To be determined) has one member upgraded to a High Helm for free.
This makes Silver Helms a few points cheaper all round.

Hopefully none of these would be considered too over-powering, as they would help Silver Helms become once more the "vanilla" cavalry of an Elven army, rather than just "hangers on"