My team at work is starting a new project, using Subversion as our VCS (you may consider this set in stone for the purpose of this question). We're still in the early stages of the project and are trying to agree on a branching model. Our previous project was based on a non-standard version model that led to issues when managing hot-fixes and patches to existing releases.
I've found different branching models to be rather complicated, but one model that I do understand fairly clearly is git flow. I'm curious how hard/undesirable it would be to implement a variation of this in Subversion. Obviously there would some difference in terms of people collaborating on branches. The feature branches would have to be centralized rather than limited to local repositories, but the other concepts of the model should be reproducable in Subversion as I understand it.
What would be the drawbacks or challenges to this approach. What I've heard is that in SVN "merging is expensive" relative to Git. But I'm not completely clear on what this means in practice or how it would effect our ability to use a git flow like branching model.
What would be the biggest concerns with this approach. Is there a similarly clear approach that is more natural in Subversion?