First off, don’t assume that higher voltage means more speed - if your cells don’t have a low Internal Resistance, all bets are off. It’s all about Ohm’s Law… The owner of the hobby shop I used to buy from back in the day used to say, “At your level of competition, batteries win the race - don’t spend your money anywhere else if you don’t have the juice to drive it.” Believe me, back in the days of matched and graded sub-C cell packs, better batteries quickly got me up from the C mains to the top of the B’s statewide, and winning series’ at my local track. Anyway, IMHO, it’s just a matter of time before the sanctioning bodies just allow charging to 4.35. I think the biggest driver is that as cells deteriorate and people end up buying new cells (LiHV), there will be less worry and pushback about people having to buy new packs.
I wouldn’t go around saying that LiHV’s are just glorified LiPo’s though. By classifying them as LiHV’s, the companies are basically assuring you that you can charge it to 4.35/cell SAFELY (as safe as LiPo’s cells can be, anyway). I know that I wouldn’t feel comfortable charging a standard LiPo cell to 4.35V. Care wise, I would just charge them to 4.20 (if competing under current sanctioning rules, special allowances excepted, of course), and store them at 3.8V, or whatever voltage works for you (I know people have differing opinions on that)… but I predict that one day soon, ROAR and the other sanctioning bodies will raise the ceiling to 4.35V when they think it will have minimum impact on the user base.