I would concur. Especially if you are going to make the subscriber the TFTP server, it needs more horsepower.
The 7835 will take a little longer to do backups, but it shouldn't be that much longer.
Also, you have to consider CAR/ART as well. Depending on the size of your disks, you might run out of space.
On the otherside, it's a lot easier to upgrade a subscriber than it is a publisher. Simply add another subscriber and remove the other one. If you ever want to upgrade your publisher hardware, then you have to take it down and restore from backup.
Tough call. Is one older than the other and will likely be end of life sooner? If so, I would make the one that is more likely to be EOL'ed sooner the subscriber. Just to make the upgrade process easier.
Also if you are thinking of upgrading to v5 or v6, make sure the publisher hardware is supported.
It is always the best option to have the Publisher on the latest hardware along with giving it more power. So when u go through upgrades in future, you dont have to worry about migrating data from one server to another and wit the subscriber, it is not hard to remove a old subscriber and add a new server.
With 80 phones, 7935 should not have any problem handling the load
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.