The TM22 MJN is probably the best carb in this size range. That said, the deal-breaker for me is not the price tag but the uncertain parts availability. I wouldn't mind an expensive carb, if it delivers improved performance, i.e. seamless throttle response to go with top speed, as long as it can be serviced when/if needed. It's a JDM part, no authorized US distributor...whom, ostensibly, would stock parts.
If the rumors of the VM20s imminent demise are true, service parts (seals, gaskets, inlet needle/seat, jets) are likely to be available for years to come and cheap enough to stash a few for the future; it's marketed through Mikuni USA and Sudco.
Only downside to the PE20 is its cost...double that of the VM20 and it's a spigot-mount. A rubber-coated mounting flange has to be sourced separately and they're not always easy to find.
BTW, I agree with Jarred on the top speed issue. On a 60mph bike even a 10% flow restriction (which is huge), caused by an undersized carburetor, would only cost ~2mph at the extreme top end; a stiff headwind would have far more impact. On an engine making less than ~12hp+/- (enough to easily reach 65mph), there's no way a 20mm carb would be flow restriction, especially if port size is 23mm, or less. On the other hand, just upsizing from 20 to 22mm does increase venturi cross-section by 21% with a corresponding 21% decrease in airflow velocity through the carb. That's what impacts throttle response, especially at light-throttle/low rpm.