Just finished installing a Jard trigger in the second of my two No. 1's. Total time, from stock removal to final trigger adjustment took approx. 20 minutes.
If you follow the instructions closely, it is a very simple process. I ordered a 1.75# trigger pull, this one registers right at 2# on my scale as adjusted- perfect for me.
If you own a #1 with a crappy factory trigger, this the cheapest, easiest way I know of to really improve your rifle. All you need is proper tools, which means a punch set, screwdriver for buttplate removal, a couple of small allen wrenches for trigger adjustment, and a socket wrench for removing the stock bolt.