Wont do any harm - I've used Quark since it was Quark 2.12 and have only just changed over (got CS2 on a Photoshop upgrade). At first its a bit daunting but once you've rearranged the key strokes to the sort you've used for Quark it becomes a lot easier. The hi-res previews, printing sep previews, link updating etc are just so useful I've not missed Quark one bit. Seriously.
We output to a Canon CLC 3220 using Quark and it pushes the tick marks off centre so backing up a job is a nightmare as we have to off-centre the reverser page. With InDesign it backs up perfectly first time and processes quicker - that in itself is worth its weight in gold.