Canister good. Vents your gas tank. No performance penalty, other than lugging it around with the Jeep. Minimal maintenance.
Lots of old threads about this if you search.
If you remove it, you need a vented gas cap. Gas vapors will vent through the gas cap, like they did before the 60s. Gas will leak out of the gas cap on severe uphills - that's unavoidable with no vapor recovery (canister). You could have leakage at the cap from slosh at other times.
1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D