I have noted most people talk about using bolt-on breakers with panelboards versus plug-on ones with loadcenters. Simply asking for a panelboard design does not guarantee bolt-on breakers. If you want bolt-on you must specify it,
My experience with Cutler Hammer CH and Square D QO breakers has been far fewer failures do to plug-on connections than with loose/stripped/cross-threaded connections when using bolt-on breakers.
I trust a factory built plug-on jaw more than an incorrectly field installed screw connection. But I do understand the concerns with the reinstallation of breakers and with "cheap" designs (i.e. FPE) especially on some aluminum bussing (i.e. Zinsco).
