thanks all guys, it seems concluded that, with proper control, mosfet can be made as pass element in linear mode regulator just as good as bjt.. i guess, from understanding the replies here... as i'm currently designing my linear regulator psu, i bought TIP142 darlington bjt. its rated 10A, but big TO-247 package. and i also have IRF540 nmosfet rated 28A, at normal (smaller) TO-220 package, so from amperage per surface or footprint area (and i believe cost saving), mosfet is more advantageous, i need 2 of TIP142 for 20A rating which took more space on the PCB. but as my linear psu design already get involved using the bjt, i will continue with bjt, maybe on revision 2 next time, i will consider using mosfet. thanks all.
(ps: to be more accurate, my current psu design is following exactly like the LM317 setup above, with paralleled bjt's using 2x TIP142. yes its a normal bjt with no over temp protection, but i think i will take care that in the design such as limiting the power (current) consumption, or maybe temp sensor on the heatsink, fwiw)