If you read a lot of reviews (and I did) and you are comparing the same models (HDMI wireless standards are not all the same, and even when they are there are some poor implementations) you'll see quite a lot of them were when the reviewer tried to transmit through walls, or had it next to something that blocked signals otherwise. Amazon reviews in particular.
I still firmly believe the Epson UBE is a waste of money - it's more expensive then standalone units, locks you to that PJ (since you can't buy an upgraded unit with *just* the receiver you're paying for it all over again if you do), and anecdotal evidence aside there is no concrete testing that shows it's "better" in any way. Stick to a well-reviewed unit like the IOGear (DVDO makes a decent one too, I understand) and you'll be fine. I'd be willing to bet that if you have problems with a good standalone unit you will have the same problems with the UBE, it's not magic.
But each to his or her own, I'm only relating my experience. Around Christmas I'm probably going to upgrade my A/V receiver and re-run my cable anyway - and when I do, I'll be able to re-use my wireless unit I'm already thinking it would fix a problem I have in another room.