...but the issue that etrex has is the number of track points generated in the GPX.
Never used Garmin connect to create tracks before, but does it really manage to hit the eTrex trackpoint limit on anything that's not a huge distance?
The limit for trackpoints is 10,000 per track.
Depending on terrain, and the twistiness of the roads, tracks I've made from other sites (BRT, bikely, bikehike, ...) typically come to ~1000 points or less for a 50+ mile leg.