Been using this for a little under a month now. I am currently running 3 profiles (ubercart, amazon, and ebay)

I set the whole thing up myself. As far as getting it integrated with ubercart it was pretty easy (it was probably the easiest out of the 3 stores I set up). The 30 day support really helped since there were a lot of rough edges that needed to be smoothed out. To be honest I am probably going to buy the annual support plan because it seems like Ebay and Amazon update their site so much there will probably be an error somewhere in the future.

Each store gets its own profile that you have to configure and select from a drop down menu. At first I wanted everything to be under one tab but after using it for a month I see the benefits of having each store separate. I still get the occasional error but tech support is pretty quick in replying. They had to take control of my computer a couple times with gotomeeting but resolved all the problems I threw at them.

Since this is an Ubercart based site i'll touch into the pro's and con's I've dealt with regardiing ECC and Ubercart Integration.

Pro's:
-Easy installation (just ftp the module, direct ecc to your site and give it admin permissions. Also had to configure some file permissions on the server)
-Downloads and Updates orders instantaneously with all the order comments/tracking info

Con's
-Only supports default payment methods from Ubercart out of the box. If you have customized payment options you have to go into quickbooks and create new payment methods and map them
-Sale receipts can only be posted to one account in quickbooks. So if you have Paypal sales receipts and Quickbooks Sales Receipts they both have to go into the same account. They have a workaround to this that seems to allow 2 different methods to 2 different accounts but anything more than that you might have trouble. The workaround is to set paypal to download as invoices to your paypal account and credit card transactions to download as invoices which get paid due on receipt and deposited to whatever account you have. Right now personally I keep both payment types deposited into undeposited funds and I run through them and manually deposit them myself. I'll probably switch over to the above method in a couple days after I make sure it doesn't effect my Accounts Receivables in any way.

Conclusion:
My order processing time/ quickbooks entries have basically been brought down to 10 minutes a day. I find myself sitting around bored because I ran out of things to do. It was well worth the 600 dollars (I got 3 licenses and inventory module which I haven't used too much yet) for the time it saves me alone. Keep in mind the initial configuration will not run 100% straight out of the box (unless you are lucky) but the support staff is awesome and are really on top of their stuff.