Anybody can relate experience ( good or otherwise) with refined product radar tank gauging systems such as Endress & Hauser FMR5xx , Saab -Rosemount REX RTG3xxx.
My experience with the Ohmart Vega PULS62 has been very good. We actually used the small holes where gauge tapes were previously hung for several tanks. In a few places the connections were very tight for the horn (1.5"). We have used a similar line of radar transmitters with a much larger antenna for polyethylene pellets etc. K-Tek also sells competitive level instruments. I think that they have radar in their bag of tricks too.
If it's not a "special" application my advice is to go with the one with the best support (rep, factory help, etc). I'll take support over reputation anyday.
Not wanting to sound like their sale representative, but Ohmart Vega visited each of the plant sites where I have bought their radar level instruments. They frequently call on the control systems engineers in my office. As for the results, I am unaware of any field problems.