The negatives would be the cost for the conversion. As for resale, I think there will always be a market for a genuine HK94 that has been converted to a SBR by a reputable gunsmith. I also think that market would allow you to recoup your investment as long as you didn't use your $13,000 NIB HK94 for the conversion.
To me the biggest negative of a F1 is the engraving. I have seen some really ugly jobs.
For SBR/SBS always when you can engrave the barrel so that the markings in a way can be removed if going back to a title I
HK KI MARK 23
HK KI USP45 Tactical
HK BG USP9 Tactical
HK BG VP9 Tactical
HK BG SP5K(MP5K-N)
OP I would check your options for the build and DO NOT have your barrel cut and a tip applied.