They are a great module, great with the probability for introducing random triggers, something nice is to shoot the triggers to something like Rings or the 2hp Pluck or Bell via the 2hp Arp and Tune, Makes for some pretty results.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.