Just my own personal 2 cents worth here:

I agree with others that hi tap isn't going to hurt anything from what I've seen and read. However...

My first table was (and still is as I will NEVER sell or trade it) a 1976 Williams Space Odyssey. When I got it I was very unhappy with the responsiveness of the pops and the power of the flippers. I was considering hi tap then and started reading about it. While doing so I found what you are finding in this thread - lots of people in the hobby advocating the rebuilding of the assemblies in question to ensure that they were working properly. In the end, that is what I did and I don't think I'd ever switch the table to hi tap. Why? A few thoughts, and I share them just because I wish more people had been this clear about things in threads I was reading at the time:

OK, Flippers first. One of the things that I read here on Pinside a few times during my initial research that really struck me was the idea that your flippers are your only point of interaction with your table and are the only thing that you really have control over. Since this is true, make sure they work the best they can. Once I had purchased a Williams Flipper Rebuild Kit from Steve at Pinball Resource and then done the work to rebuild them, I found that they functioned better than before. Significantly better. Waaaaaay better. Better to the point where I was kind of shocked. That flipper rebuild kit cost me $53.84. I'm just trying to state in as enthusiastic terms as I can that this was money well spent and that those people on Pinside were right. Don't be afraid to spend that money because I highly doubt that you would ever regret it.

One Pinsider has done a great job breaking down how to rebuild flippers. Here is his guide:
http://pinside.com/pinball/forum/topic/vids-guide-to-upgradingrebuilding-flippers

As far as pop bumpers on a late period Williams EM go, just re-read my comments above regarding flippers and insert "pop bumpers" whenever you see the word flippers. Everything else is just as true except the part about having control of them. Also, pop rebuilds were only about $10-15 per pop. Very inexpensive and I was just as shocked at the improvement. Again, don't hesitate. Money well spent, I assure you.

Here is a guide about rebuilding pops:
http://pinside.com/pinball/forum/topic/vids-guide-to-rebuilding-pop-bumpers

The one thing I would add is that it was really important to finish these rebuilds correctly. In each case this meant adjusting the associated leaf switches/end of stroke switches after they had been replaced to get maximum performance out of those parts.

Seriously, I can't encourage you enough to do this stuff. I really think you will love the results. I only wish I had done so sooner with my Williams EM.