Aerobatics will make you a better pilot, improve your co-ordination and confidence, and make you better able to get out of buttock-clenching situations, should they ever arise. And don't worry about being a low-hours pilot: the RAF introduce students to aerobatics relatively early, way before they reach equivalent PPL standard.
IMC is a get-you-out-of-trouble rating only, and doesn't equip you with the skills you need to fly deliberately in cloud. Of course it's a worthwhile thing to do, but I think you would get a lot more out of doing the aeros.
My advice is to do both, but start with the aeros first.