Machaka and a W9 bless

[archaeolept]

it may well be that these kinds of Machaka builds are not particularly effective late game

It is not that they are not particularly effective late game, heck they won't even still be alive then, but that they're not very effective in the early midgame. The spider riders are so vulnerable to pretty well anything other than indy chaff, and the spiders themselves have such absolutely pitiful MR, that they tend to be massacred w/out much difficulty by any human opponent. Poison, lightning, fatigue attacks, most other sacreds on any gp/resources matchup...

The require a massive investment in points, gold, and resources. They are then effective only against opponents against whom almost anything is effective...

I like the sacred spiders, thematically, but size 6 and 125 gp kills them. personally, i'd up spider MR by 2, lower cost to 100, and increase rider defense by 3 - it's gotta be difficult to hit someone sitting on the back of a giant tarantula
Even then, they'd be a bit borderline for a serious bless strat.

The hoplites, backed by the web spitter spiders and bows, work well. flaming arrows and magma spam give machaka good midgame power.