Well, the Audiomods Arm is a modified Rega only if you consider the tube of an arm the one and only determiner of what constitutes an arm! Unlike other Rega "based" arms, Jeff uses only the Rega arm tube in the arm he hand machines all the other parts for, and the arm tube itself is re-engineered to such a degree that it can hardly still be considered a Rega. He does NOT use the Rega yoke, bearing assembly, bearings, main pillar, plastic arm platform, anti-skate, cueing platform and arm rest (except in the budget Classic model), counterweight or it's stub.
In place of all the other parts which comprise a Rega arm (which he does not get from Rega---he buys only the arm tube---with one inconsequential exception, noted below---from Rega), Jeff hand-machines from billet aluminum a new yoke of his own design, new bearing assembly, new main pillar, platform for the whole arm assembly, thread & weight anti-skate, cueing platform and arm rest (except, again, in the Classic model), and adjustable mass counterweight and it's stub. In addition, he makes a new armboard mount that his arm slides into, allowing height and VTA/SRA adjustment of the arm. He replaces the Rega steel bearings with ceramics, and offers a precision Micrometer with calibration that allows on-the-fly VTA/SRA adjustment during play. The Rega 303 arm tube itself undergoes extensive re-engineering, as detailed previously.
If you consider the Audiomods Arm a modified Rega, I don't know what I can say to change that perception. This is a misconception Jeff still has to deal with, no matter how many times what I have just said is repeated. Does the fact that the arm tube, and the arm tube alone (with the exception noted above) is sourced from Rega make the arm a "modified" Rega. The answer is, I propose, obviously no. If Jeff made his own tube (of which there is no need---it's a great tube, far, far better than that found on, for instance, all the Jelcos), there would be NO connection between Audiomods and Rega arms. The rest of the arm, in fact it's entire design and construction, is COMPLETELY different from a Rega.
If I had $700 to spend on an arm, or even $1700, I'm not aware of another arm I would rather have than an Audiomods, whether the budget Classic (455 Pounds---$705) or the top-of-the-line Series Five (625-675 Pounds with silver wire, an additional 120 for the Micrometer). They both seriously out-perform their competition, as many satisfied owners will tell you on the Audiomods website, some of them also owners of other far higher priced arms as well.