I tend to agree with moorcrys that cleric casting may be a bit underpriced XP-wise. Spellblade’s XP progression in particular concerns me - barely slower than fighter, full casting with none of cleric’s weapon restrictions, and the only thing they lose is ~1 HP / level. I could very easily see bad blood in a party with both a fighter and a divine spellsword. Sure, max level is lower, but that doesn’t come into play in most campaigns. In any case, I think I’d prefer the divine spellsword with d8 HD; then he is very literally a full fighter and a full cleric, but the XP gap between him and the fighter is a little bigger (I believe the primary reason that arcane spellswords only have d6 HD is because 4500 XP to 2nd was deemed too damn high).
One thing I think it is important to remember while picking spells for divine lists is that the cleric list is mostly specialized utility and support spells and, unlike a wizard, a divine caster cannot readily upgrade his list away from specialized tools towards more generally-useful tools. One thing I see looking at the nightblade conversion (and something which, looking back on my Valkyrie, I was no less guilty of) is that the spell list is stacked with reliably good spells compared to the cleric list. Basically what I’m getting at here is that I think there should perhaps be room for some judgment calls on divine XP value based on the general quality of the spells on the list - cleric spellcasting is cheap because there’s a lot of party-support (remove conditions, divinations, protection from/resist/dispel X, bless/prayer, create/purify food and water) and situationally useful stuff like Snake Charm, Feign Death, and Quest on there. Direct offense and single-target combat (vs defensive) buffs are relatively rare. With a fast-leveling cleric, the entire party wins, because most of his spells aid everyone. The divine nightblade’s list seems to be focused primarily on increasing his own capabilities, and where the spellblade’s differs from the cleric, it seems to be almost entirely ‘upgrades’ in terms of versatility and punch (charm monster > atonement, skinchange > speak with plants, call lightning and fire, invisibility, and winged flight > locate object, feign death, speak with dead, and glyph of warding, … Polymorph self vs insect plague is sort of debatable, but insect plague is much more situational because it’s wide-area, indiscriminate, and hard to control).
In sum - I think divine value is balanced for a spell list composed like the cleric’s, of mostly support and situational utility spells with a handful of general-purpose offensive spells or direct / single-target buffs (spiritual weapon, striking, flame strike, smite undead, strength of mind). When one starts cherry-picking from across multiple divine lists and pulling in arcane spells as divine at +1 level… maybe not so much.