UEC is really for dedicated machines, that is, you setup some machines to be a general compute resource, and essentially, every core in that machine can then be available for processing. You could use something like gclusterFS so that all nodes can access the same set of data and so on.
Condor on the other hand is more about the idle machines, i.e. Seti@Home or Folding@Home, though you can dedicate machines to always be available.
But its no so much that Condor is a pain to setup, as the application you want to use may be a pain to setup. Let's say you're, I dunno, analyzing genomes. Well, each running copy of the application would probably need access to the genome, which might be say, 4GB. So to start up the processing, Condor might have to copy 4GB to the running copy so it can work on it.
The setup costs really has nothing to do with Condor, its about the complexity of your app. Condor is just a toolkit to do some of that heavy lifting. So you would setup a job with Condor to say "I need a machine with 64 bit addressing, and 4GB of free disk space). When a node became available, Condor would farm the job out to that node.
With Condor+UEC, some of those available nodes could be part of your UEC cluster. If you were servicing several types of internal customers, you could make different flavors of nodes available: Some with more cores, some with more disk, some with GlusterFS, etc. Then someone can submit a Condor job, Condor would figure out which of the available nodes are the best fit, and run jobs on those. Someone else could submit a different Condor job, and condor might match a different set of nodes. If all the nodes are busy, or none of the right type are available, it will queue the job and run it when they become available.
So lets continue with my Genome example. If you have the genome mounted on a GlusterFS disk, then you can declare that as a particular kind of resource in Condor. You would have certain running instances able to access that GlusterFS disk. Then people could submit a job and request nodes with access to the "GenomeDisk". Condor would then run jobs on those nodes instead of other nodes.
So you use UEC to manage the mix of stuff in your compute cluster, then use Condor to match jobs to nodes.
But UEC assumes non-idle machines. If you want to use only idle machines, you would have to use straight Condor. Or you can mix and match. Use UEC to manage the compute cluster machines, use regular Condor to provide raw processing without any resources.