The difference all depends.
If it is say a 7 MHz dipole and you are using it on 7 MHz then the change is SFA (Small Finite Alteration). Don't sweat about it.
The average height above effective ground is the major factor. Tilting the vee over to fit the dipole in is OK. Just get the centre and the ends up as high as practicable.
The ends do not have to be close to ground level. Indeed there are many good reasons to have the wire no less than 2.5 m above ground especially for a home antenna.
If you run the antenna on its third harmonic the tilted over configuration will be a tad more directional than if it isn't tilted. Maybe that is useful and maybe it isn't.
Antenna modelling, flat earth or not is fine, especially for NVI. It just confirms that the distortion in the pattern can be more than compensated by a small lift in average height. As I think you are talking about a home antenna the knife edge QTH does not apply.
I have used various antenna including the G5RV, doublets, link and trapped dipoles in the inverted Vee tilted over configuration over some 40 years. No one has noticed. At home the ends are 6 m agl and in the centre 12 m agl. My back yard and YF condoned mast placings limit me to about 115 ft of wire in an inverted vee tilted over shape.
Even on 80 m propagation can be significantly different at times over only 6 km or so. It is much more noticeable on 40 and above. Another chaser will sometimes give out 5x5 when I have 1x2 but often 5 minutes later I have 5x5 and he has 1x2. When sunspot counts are low the propagation footprint moves about more noticeably.
Having a temporary vertical antenna may be useful for comparison. For receiving only just put a squid pole next tho the shack window and run an 8 m wire to a change over switch. Proper earthing and matching would be required for transmitting but for a temporary receiving setup only, these can be dispensed with. The S/N ratio is more important that the signal level.