Had a couple, and I'm about the same height (and was the same weight 😂) as you.
Yes, they're flexy. That being said, realistically, how much power are you putting out? If you're a 1600w+ sprinter, you'll notice it, if you're a regular human in the 1000-1200w range, if you're not winning races, it won't be the bike flexing that's the problem. There have been plenty of people riding them at national level in the past in endurance events.
Don't really think I can answer about the sizing question, as that's such a personal thing, but that being said, 59cm track frames are really hard to come by unless you want a 220mm headtube, so you may end up having to pay for a high end frame if that's what you want. Only affordable option out there I can think of would be an XL Hoy Fiorenzuola, but those are SUPER rare, unfortunately (such a shame as they're incredible frames for the money!) Those are even longer than the DF4 though, with 538mm reach (60cm TT).
If you're not so fussed about the smaller sizing, the Felt TK2/3s are pretty much exactly the same geo as the Planet X and way, way, waaaay stiffer. And they go for a song second hand, which is nice! Bought one a couple of months ago, and it's easily as stiff (if not stiffer) than my Pinarello!
Had a couple, and I'm about the same height (and was the same weight 😂) as you.
Yes, they're flexy. That being said, realistically, how much power are you putting out? If you're a 1600w+ sprinter, you'll notice it, if you're a regular human in the 1000-1200w range, if you're not winning races, it won't be the bike flexing that's the problem. There have been plenty of people riding them at national level in the past in endurance events.
Don't really think I can answer about the sizing question, as that's such a personal thing, but that being said, 59cm track frames are really hard to come by unless you want a 220mm headtube, so you may end up having to pay for a high end frame if that's what you want. Only affordable option out there I can think of would be an XL Hoy Fiorenzuola, but those are SUPER rare, unfortunately (such a shame as they're incredible frames for the money!) Those are even longer than the DF4 though, with 538mm reach (60cm TT).
If you're not so fussed about the smaller sizing, the Felt TK2/3s are pretty much exactly the same geo as the Planet X and way, way, waaaay stiffer. And they go for a song second hand, which is nice! Bought one a couple of months ago, and it's easily as stiff (if not stiffer) than my Pinarello!