The DFII I have was a tight fit in one kdx, fine in another (both '00s).
If it took a minute to take the edge off the valve to resolve a fitment issue, then I'd do it. Big deal.
EG has far more experience with the DF on different bikes than I do. However, if a moron...I mean rider...ruins his bike with a hacksaw in the process of fitting a reed cage, how is that the fault of the reed cage mfg? There is the moron...I mean rider...input to consider after all.
And any moron..I mean driver...that thinks he's going to bolt on a nitrous system during a lunch break..one he bought from a catalog... and have it work is...well, a moron.
As far as the radvalve reference...whoever likes 'em is more than welcome to use 'em.
Considering the slot for carb location doesn't exist in the radvalve, considering there is twice the number (ha..two, anyway) of hoseclamps in the boyesen setup (more joints=more chance for leaks), considering the life of the reeds in the boyesen was terrible (less than a year), AND considering the radvalve doesn't particularly do anything..I choose to not use one.
If God likes the one he has in HIS kdx, that's fine. I still choose not to use one.
And, if you get a DFII and think the high tension setting is fine, that's fine, too. After all, it's your bike! BUT, having the choice of tension settings, it's kind'a stoopid to not at least check out the possiblities. Then you can say, 'I know...'
Rejet? Maybe. You'll know for sure when you check your bike. The same as you would with temp changes, elev. changes, or after any other modification.
The question from the start: '..would putting a delta force setup in make much of a difference in the performance of the bike...'
The answer is, 'Yes.'