Trilead Free works well for us. We have Veeam for our main ESX hosts and we use CAArc D2D for Exchange / SQL (from within the hosts), but we also have 7 ESXi boxes that run various utilities, testing servers, etc that would be a pain to recreate. We use Trilead for these ESXi hosts. 3 problems:
- Free only allows 5 hosts so you have to remove the 5th to add the 6th (for example)
- It won't do deltas for ESXi (meaning that it'll only backup the whole machine, not just what has changed.
- No scheduling of backups.
So, as you see from these 3 limitations, it's not a primary backup solution (at least for us) but it works to get a backup a week manually for our more important servers running on our free hosts. I'd probably buy the software to simplify the scheduling, it is only ~~$750 for as many hosts as you want, but w/o delta backups for ESXi boxes it is kinda crippled IMO.
Also, restoring from teh free version is a bit of a pain. If I were you, I'd install the free version and NOT get your pro trial key. Wait till you need to do a restore to get the trial :)