Brother Richard said:
Right now I would like to have Iron Heroes classes and skill chains with no Iron Heroes feats.
By skill chains I will assume you mean skill groups. No, this will not create balance problems, since all PCs will become more skillful.
By no Iron Heroes feats do you mean using D&D feats only or not having feats that are in Iron Heroes, regardless of their form? If the latter then no one would have power attack, cleave, great cleave, combat expertise, or just about any non-magic PHB feat. So I shall assume that you won't consider such a drastic step and shall instead simply use only D&D feats.
Much of the coolness and power of the classes will disappear, especially if you convert IH hit dice and saves to D&D equivalents, reduce feat acquisition to normal D&D rates and slow down token generation as recommended in the conversion guidelines. On the other hand, the classes would become balanced against all the magic bling in the setting, removing that concern.
You will lose one of the priciple advantages of Iron Heroes, though, in that there will actually be bad fighting styles again. One of the beautiful things about IH is that with the right selection of feats,
every single fighting style is equally viable no matter what weapon is chosen. Darts, shuriken, clubs, tridents, nets and quarterstaffs are just as deadly, or even deadlier, than greatswords or two shortswords as long as the character invests some feats into acquiring that deadliness; by removing those feats you will make all those styles sucktastic, again.
I gather that your intention is to replace all the non-casters in D&D with IH classes and keep your D&D caster classes. It can work, quite well even, but you'll need to figure out some powerful high-level feats so that a Man At Arms is actually on par with a caster that has 4+ 9th level spells per day. Since feats are 'always on', they shouldn't be as powerful as a single casting of such a spell but they should provide the same amount of overall adventurer power as being able to cast 4+ ninth level spells per day.
Out of curiosity what choices were you going to make regarding AC, DR, saving throws, hit die types and various sundry conversion decisions?