I installed a Crane Xr-700 on my 544 (with a 2.2 liter B20E) and replaced the coil at the same time.

The original system:
Original firewall mounted coil (with armored cable), cast iron B18 vac advance dist, points, condensor)
1) Weak spark - at wide open throttle the engine would sort of surge through the middle RPMS - I at first thought it was fuel starvation but realized that would be more off and on.
2) Wobbly timing - not that you could necessarily tell this while driving, but at idle the timing light would show the timing bouncing around 5 degrees or so.
3) Frequent retiming - every 5000 miles or so I had to re-gap the points and reset the timing.

The new system (all parts bought very reasonably on eBay!):
Mallory Promaster coil (About $25), Mallory Unilite mechanical advance dist (About $60), Crane Xr700 system (about $60)
1) Strong spark - with just the coil swap the engine immediately perked up and now pulls cleanly through the whole RPM range and strongly up to 7,000 rpm.
2) Rock steady timing - the timing light shows practically no deviation in the timing
3) No Retiming - I check it occasionally but haven't had to touch it in about 15,000 miles.

The only thing I can think that is a drawback is that IF something were to fizzle on the system you wouldn't likely be able to tinker with it and get it going again on the roadside. While a points system is simple and out in the open so you can usually patch it up somehow. Just a theoretical drawback, however.