You first need to list your requirements, excluding any software solutions. You already listed one, that is having an RTO of less than 3 hours for any VM. Depending on the size of a given VM, restoring a full vmdk disk from backup to production storage could be impossible to reach even with high-speed restore operations, so Instant VM Recovery from Veeam could be a feature to fulfill this requirement.
Other elements you need to evaluate before eventually go for Veeam are for example if your environment is completely virtualized, since Veeam cannot backup physical server; other suggestions like keeping TSM to do both could be right, or maybe you prefer to have "best of breed" and manage two backup software, or even if you need to do offloading to tape, at the moment Veeam cannot do that and you need to rely on a second software to save to tape (but Veeam is expected to have tape support in the next release)
My 2 cents.
Luca.