As an originator of the enlarge/reduce problem (and I think it is a problem) I'd like to show you my house rules for it, so you could include it for anyone that is interested.
Enlarge: Increases size category of target by one. It doesn't affect the creatures mass or attributes, but it does give the benefits and penalties of being bigger. Typically -1 hit, -1 AC, -4 to hide checks, +4 to grapple checks, increased reach (if going from M to L, for instance. Going from S to M wouldn't increase reach). Affects one creature and its equipment.
Reduce: Decreases size categorty of target by one. It doesn't affect the creatures mass or attributes. but it does give the benefits and penalties of being smaller. Typically +1 hit, +1 AC, +4 to hide checks, -4 to grapple checks. Possibly decreased reach (if going from L to M, or S to T for instance). Affects one creature and its equipment.
Thus the spells provide a measurable benefit which is easy to apply, and reflects the rules for size category without getting mixed up in the whole business of increased mass, strength, reduced dex etc. and avoids the strange half-way house which the current spells have.
Cheers