Yup!
Its just Discovery and Compliance Accelerator you have to watch for service packs for
i.e if you were on DA2007 SP2 you would have to go to DA 2007 SP6 and then 8 SP5
But with EV you can go from any service pack on one version to the next major version of any service pack

So EV2007 SP1 to EV8 SP3 or EV2007 SP2 to EV8 SP1 etc

Its always recomended to upgrade from latest service pack of current version to latest service pack of next version. So request you to update to latest version of 2007 and then go for version upgade 8 SP5.

Where did you hear that?  As JW3 said, the main issue is when dealing with CA and DA, but for EV 2007 to EV 8 you can do straight upgrades.

There was one caveat if you were EV 9 sp 3 going to 10 but since EV 10 sp 1 is out that isnt really an issue any longer.

You can refer to this:

Supported upgrade paths for Enterprise Vault (EV), Compliance Accelerator (CA), Discovery Accelerator (DA) and Discovery Collector (DC).

I did hear from the support last time when I contacted them to get suggestion on upgrade path. As you guys seems 'Trusted Advisor' I dont have any more comments

We do have DA running in our enviroment. Here is DA version info.

In registry it shows 7.5.5.5359 and in DA admin site it shows 2007 (7.5 SP5 revision 002)

I look at the chart in article TECH53174 and I believe I cannot upgrade EV 2007 to 8.0 SP5 directly. I believe I need to update DA to SP6 first. Can any one confirm if this is true.

Thank you.

Yes, you will need to upgrade DA to 7.5 sp 6 first and then go to DA 8 sp 5.

Thanks everyone for help.