Having owned a Spector 5 and an MTD 5 (albeit the cheaper models ) I think they are very difficult to compare to each other - a bit like trying to compare a Fender to a Gibson, for want of a better example. Great in their own right, but a bit like chalk & cheese.
With the kind of money you're talking about spending, both would be very high quality basses but you would need to play examples of both of them first to be sure of what you actually prefer. Gwilym's offer of help is really worth taking up if you can.
IIRC, the Spectors have narrower string spacing for a start and that makes a huge difference to the feel of a bass..and the MTDs have an asymmetrical neck - again, very different to a Spector.. And that's before you compare anything else like woods, body shape, neck, electronics & pick ups etc, etc..
Good luck with it all - should be a lot of fun!