I'm just gonna get back into this Rabbit Hole debate a bit more.
In a "normal" meta I think 4 link is fine. You pay 1 to bypass an ICE if the corp doesn't boost, and in the rare occasions they do all that link you have is just worth 1 credit each.
However, in a tracer heavy meta that we're in, having more link is beneficial because it pays off multiple times each turn. 4 is still plenty, but having more cards that provide link makes sure you get to 4 earlier. Access to Globalsec is ideal here because you can just drop it for 1c and it probably pays itself back the next time you run. 1 Access and Nexus, and you're at 4.
When it comes to Rabbit Hole, it is the most efficient way to get 3 link but if you do not play it the moment you draw it, every draw thereafter has a risk of drawing another one - and if you do, you've just lost 2 clicks worth of efficiency by wasting a draw and another because Rabbit Hole only installs copies from the stack, so you have to install from your hand normally. However, to make sure you avoid this, you have to have 6 credits that you absolutely do not need at the moment and my experience is that this just is never the case. That 6 credits would allow you to drop a Sherman and bust a wraparound.
Another problem with the high play cost is that the Rabbit Holes will clutter your hand which is a real problem in Sunny because you're already holding onto any breakers and Nexus until you need them. Sports Hopper kinda shares this problem, but Access to Globalsec does not. I guess this is less of a problem with The Supplier, but I'm not gonna host my important stuff on any resource once Hatchet Job rolls out.
Power Tap is a card that is also meta-dependent. I would not play it if tracers weren't abundant. With Power Tap you ideally want 5 link - that way they will be at least Underworld Contacts when Nexus is used. In a meta wirth Resistors, Turnpikes and other traces that you can walk through with 5 link, Power Tap makes stupid bank.
So if rush and glacier with mostly hard ETRs and other traceless ICE take over the meta, I would shed any excess link and just roll with Nexus and Hoppers.