The issue with the Evo is so evident it's scary, example:
Got my S3 the other day, as weird as it sounds after buying an s3 used and rooting it, I still loved my Evo and held off a day before activating my S3. After using my S3 on my account for just a day, my S3 actually maintains an LTE connection at my home more often than a 3G one. Something I've never seen even when I was using my Galaxy Nexus which I thought did a fine job with LTE.
Even rode around a little today and as suspected, 4G dropped in and out in covered areas no problem (on the S3). For crying out loud call quality even sounds better on my S3. I'm just not sure anymore, maybe out of nowhere Sprint/HTC will release a JellyBean update that will fix the connectivity issues in one solid shot, I'd happily jump back on my EvO.
Side note : when I did the airplane toggle trick, I'd see full bars of 4G connection at times in certain spots but my download speeds would be horrible (.467Mbps down on my Evo)