You should be cautious about taking advice from sales people. Their primary job is to sell what is current. The iMac i7 has been recently updated. It is well regarded. The Mac Pro is expected to be updated "soon". I would be very surprised if not within the next six months. The advantage the Mac Pro brings is greater flexibility, greater expandibility, more memory capacity, more internal hard drive capacity, state of the art technology, etc. (for a premium price). A question: Why limit yourself to the entry level Mac Pro? You are comparing the top of the line iMac with the bottom of the line Mac Pro. You are also comparing a very late model iMac with an aging Mac Pro due to be replaced soon. So the comparison is not apples to apples. However, if you are OK with focusing on existing software and existing capabilities, then it may make sense. Personally, I would be shocked if Apple did not introduce an upgraded Mac Pro within the next six months that would knock the socks off the iMac in terms of all around capability, flexibility and expansion potential. In addition, from what I have read, Apple has severly crippled the iMac from the perspective of upgrading the internal hard drive should it fail or otherwise need to be upgraded via proprietary software. So, while I cannot answer your specific question I think the iMac is very limited as a serious long term production platform. Just my take...
