I think what you'll get here in these forums are varied opinions about both antennas.
Some will have tried both with one person liking the ST2 antenna and another person will like the Discone.
Personally I have only used a stock antenna on my BCT15x and upgraded to an ST2 a short time later.
The ST2 improved my reception immensely.
I live in an area (GMV) where mountains are part of the landscape and the ST2 was pulling in 5 bar signal strength where the stock antenna for the same frequency was getting 1-2 bars signal strength. I'm talking 40-50 miles away.
I mostly listen in on the 151.000-163.000 range and the 453.000-460.000 range for frequencies.
I don't listen to anything in the 800 MHz range.
You'll also get varied opinions on the type of coax you use and the length.
My ST2 came with 50 feet of RG6 coax, I used all 50' of that and had to add a few more feet of coax left here from the Adelphia Cable days. You read my results on performance earlier....
Comparable to actual LMR400 at half the price, sounds like a deal to me. Best advice: get "the good stuff' and do the setup right the first time, that way you won't end up regretting it later on and having to not only spend more money but redo the whole feed line a second time.
That's about the minimum grade cable I'd use for a 100 foot run. It's not true Times Microwave LMR-400, and I'd take their specs with a grain of salt. Personally, I'd go for the real thing if you can afford it.
You can spend a bunch of money on an antenna, but if you use low grade coax, you'll lose what you gain. Since installing an antenna can be hazardous and time consuming, going cheap on coaxial cable can be a real pain in the butt in the long run.
Make sure you figure in the costs of the connectors. Get the professionally installed when you purchase the cable unless you have experience doing it yourself. An incorrectly installed connector will cause no end of headaches. Also figure in proper weather proofing of the connections.