The fact that anyone is still climbing on 1/2 inch line with a split tail should warn you right now that they are old school and aren't interested in learning anything new or doing anything the easy way. If they are climbing on a closed system, well I don't even know what to say about that.
1/2 inch line weighs more than smaller diameter and any extra strength it offers is beyond the ANSI and EU standards. I use lava which is 11.5-11.7. It's slightly smaller than 1/2" line, but weighs 30% less than most 1/2" lines (4.7lbs per 100ft I believe). The weight becomes a lifesaver when lifting tools aloft. It also has considerably less stretch than lines like highvee, safety blue, etc, which is also a big deal when climbing.
As far as the split tail, get rid of it and get an eye to eye. Even the schwabish is better than a blakes hitch and thats saying something since it's the worst knot you can tie with an eye2eye. E2E's keep you closer to your rope so when you sit into your line you don't drop down as far which is useful in any number of ways. Not to mention once your done using it for climbing you can use it as part of a self tending 3to1 or 5to1 to pull a tree over
Sorry for the rant.
As far as lines go, I'd suggest lava, poison ivy, velocity, or blaze.
As far as E2E's, I'd suggest tenex, ice, or technura
Oh yeah, as has been stated before, you most likely mean, spliced eye. Well worth the money, on at least one end, some lines you can get both ends spliced.