What's the difference between the ST-LINK/V2 and STX-RLINK programmers?
Both should be able to debug and add breakpoint. I believe STX-Rlink works with the Raisonance compiler only which is based on the GNU C compiler. The free compiler is limited to a few breakpoints. For the ST-link, you can get that working for popular ARM compilers like Keil and IAR. I use Keil quite often with ST-Link. The evaluation version of the Keil and IAR is code limited to 16k I believe.