I have a SPARC on my VZ58 in .223 and a TRS-25 on my CZ858. The SPARC is definitely bright, but it is not able to mount as low as the TRS. Personally, the rheostat on the TRS is more to my liking, and the 2032 batteries are much easier to come by than the 2354 that the SPARC needs. Both units offer very good battery life. The TRS has a more solid mounting option, but the SPARC comes with a pile of spacers to mount at different heights. As others have said, use locktite though (which you should with all optics).
The TRS is smaller than the SPARC, if that means anything to you. I have never had a problem with a TRS and would buy another in a heartbeat if I needed another optic of that type. I would really like to try a Zeiss Z point though when money is a little more plentiful. I have not had the TRS's dot wash out on my in sunlight, but maybe I have not encountered the right conditions yet. I will admit that the SPARC is bright and I was out shooting it this week in bright sunlight with snow on the ground and had no problem. That is the real test of a red dot to me.
Can't go wrong either way in my books. There are some really good deals on TRS's these days too.