IOTL the count of Berg wasn't able to claim due to the competition of the count of Gelre & Zutphen. He'd need allies ITTL too, however the duke of Brabant will be a bit less interested than IOTL.
Limburg wasn't particular large, even though its' ruler held the title of duke. For Brabant controlling Limburg meant a greater control on trade and other contacts with the Rhineland. It also meant adsorbing the rival claimant to Lower Lorraine (by this point mostly titular and honorific).
Both Berg or Gelre-Zutphen might ITTL end up as being considered a part of the duchy of Limburg.
For Brabant Limburg-Gelre-Zutphen would be a greater rival than Limburg-Berg, however both options will be interested in increasing their influence (or more) in the Rhineland over Kleve/Kleef, Jülich/Gulik, Mark etc.
More than territorial gains, the acquiring Limburg would mean obtaining a higher noble title, however unlike Brabant (as heir of Lower Lorraine) they wouldn't immediately rise to rank of a prince of the Empire (Reichsfürst), however a stronger position could help to obtain it. Since they already are a duke, becoming a 'Reichsfürst' will naturally be their next objective.
This also means that in terms of the balance of power, certainly initially there wouldn't suddenly be a major shift; but if they play their cards right, they could gradually become more important.