That makes sense. My understanding is that fast-sync holds more in memory. So if there's a sudden crash, the current progress has nothing on disk to recover from. I think I only saw about a 20-30% difference with it enabled. Not worth losing more days over.
Discussion
Yeah, give it a shot without the boost. I think that’s what causes the crashing. At least it was in my case over a year ago.
ElectrumX continues to treat me well, except for the undocumented biannual database compaction issue.