There are no game breaking bugs you will be guaranteed to run into without the patch, so you do not
need to install it. The patch does add a second quicksave (you can increase that number) and other bug fixes and enhancements, so I would recommend installing it.
For example, in an unpatched game Finnigan's magic lockpicks will break if you use the Lockpick skill with them in your inventory, and will disappear if dropped on the ground. These lockpicks should be unbreakable, and give you a +20 agility boost while in your inventory. If you install the patch after they break, they will be placed back in Commander Kratus' desk, to be re-stolen. If you install it after the game is started, they will no longer break (so you don't have to carry around a stack of normal lockpicks), but will still disappear when dropped on the ground. In either case, you have to choose between returning the magic lockpicks to complete the quest, or keeping them to use yourself. If you install the patch before starting the game, the lockpicks will not break and can be safely dropped on the ground. You can also complete the quest, and then buy them back from Finnigan.
If you decide not to patch the game, you might want to check out
QUESTBREAKERS AND MAKING DIV LIFE DIFFICULT - most issues are fixed in the
patch, or there are other workarounds