I have an iPhone 7 and run Arccos Caddie and the Grint at the same time without issues. I try to start the round as fully charged as I can but am usually at 40 - 50% charge at the end of the round. I haven't tried to use it for 36 holes without charging yet. I rarely open Arccos while I'm playing and only use the Grint for scorekeeping and stats so I'm not constantly opening and/or running the maps. For quick yardage checks I have a Garmin s10 GPS watch.
I haven't had any issues with carrying my phone in my front pocket and I don't think it's missed a shot in the 7 rounds that I've used it. That said, I ordered a Link when they came out and received it this week. I haven't had a chance to use it yet but have a question if some of you have...I read that to set the pin position you just have to stand next to the pin and press the W button. Do you have to do that before your first putt or just before you leave the green? I determined not to let my tech stuff slow down my play so I'm hoping I don't have to walk to the pin before I hit my first putt.