I use a very similar system to Charriots...., I have two "double" blocks, one attached to my harness (arborist harness) & the other block (double with a becket) I send to the top of the mast on a spare halyard, on the tail instead of the cleat, I'll tie a Prusik knot
www.animatedknots.com/prusik-knot to my harness.
As a back-up, I'll cleat the headsail halyard off hard against the mast (all my halyards etc are external), & use a second Prusik on that.
You pull down the tail rope of the system, lock it with one hand under your arm then slide up the Prusik.
Its basically the same as what a lot of Arborists use, except with the addition of the blocks to make it easier.
You simply twist the Prusik knot to descend, once you let go it locks & stops, so you can work hands free, twist the knot again to descend again. The only downside is, you have the double block system "above you" so to speak, so its not super easy to work above the mast head. You need to take a separate line line with loops in it, to step into when at the top.
Once your up & enjoying the view, you still have to get down!, make sure whatever system you use, you can get down safely, easily & quickly, without the need to disconnect.
cheers