Where to go to get help choosing the right ReadyNAS?

You posted in the right place, not sure why you got no responses. I saw your post, but didn't answer since I am not a mac guy.

It depends on how much data you have and how fast the volume has been growing. You state you have a Mac environment in your previous post and are using AFP. AFP is one of the standard file protocols and is enabled by default along with CIFS, although both can be turned off.

You state that your "core data volume is 300GB", which is fairly small considering the size of today's drives. However, you then stated that you wanted to use the balance to back up the 5 work stations. Most business locations will generally store all their data on the server rather than the workstations. That way if anyone else who has a need to access the data, they can.

As to the remote backup that can be done and there are posts on this forum about it, although I do not do it.

If you have need of the business features such as active desktop then you should concentrate on the Pro series. If your total volume need is less than 3TB and not likely to grow, then the Pro2 would be a good choice, although I personally favor the 4 bay units for expandability and the LED front panel. You can certainly start with only two drives in your array and add additional drives to expand your volume as needed. It is unlikely that you will need the 6 bay units for your need unless you anticipate the total volume exceeding 9TB in the near future.

As to which model offers the features you feel you will need, you can check the comparison charts for the business units (do not bother with the models that are 2100 and above as they are rack mount enterprise units) or the home/small business/prosumer units coupled with what your budget will support. FWIW, I'm not a Mac guy either, so I always turn AFP off and stick with CIFS.

I also would favor the Pro 4 for a small business. The warranty is better than the ultra, and since two drives are enough to start off with for your data volume, you have easy expansion.

The pro also includes rsync over ssh backup, which potentially could be used instead of replicate if you wished.

You should also use a UPS to power the ReadyNAS.

I'd go with the Pro 4/6. Personally I prefer the Pro 6 for the extra drive bays and the optional dual-redundancy but the Pro 4 is still a good choice.

Getting two 4-bay units or two 6-bay units would be good. Also note if one unit fails (assuming it's the chassis not the drives that fail) you could shift the drives over (http://www.readynas.com/kb/faq/boot/how_do_i_migrate_disks_over_from_an_existing_readynas_to_another).

Rsync over SSH is a good option, secure and easy to use and sounds like the right choice for your needs. The main advantage of Replicate over Rsync over SSH is having multiple revisions of your files, so if you accidentally damage a file or delete it you can recover the file from the backup say a few days ago. Also Replicate doesn't require opening any ports.

I use Macs and find that the ReadyNAS works well with them.

What data will you be backing up over the web? Just the core data or the Time Machine data as well?

What are your internet speeds like, especially the upload speed at each location?