I can share some personal experience that may be of limited to no value. all of this is personal opinion, but so is everything about the fountain pen.
The reason that I suggested Scubaman Rich was because of his specific knowledge of the Pelikan nibs. Back in the days before anyone else was even thinking about upgrading fountain pen nibs, Rich was experimenting with using the available commercial nibs, and I do remember his sharing some experience with the Pelikan nibs.
I have been using the Bexley medium nib in the Baron. It is the same thread that is used on the Baron, American Classic, and several other kits. It is a direct screw-in replacement. You will have to call them for priceing, but it will be less than $100.
The advantage of the Bexley is that is decorated and people do prefer decoration over a plain nib. The Bexley name is held in fairly high regard among those of the pen world, and having their name on the pen is a feature that sells well for me. You can screw it into the pen without having to tear anything apart. It only comes in a medium tip, but that is finer than the kit medium, and it can be customized into almost any width and degree of flexibility. It is a pricey piece of work, but the combination of Bexley AND Mortishaw gets peoples attention, and I would like to have their names associated with a pen if I were persuing that market.
Something you might want to consider. I think the stock plated steel nib in the El Grande is the smoothest writing kit pen available, period. And, it takes an ink no better than the Parker "Quink" that I buy at Office Depot to get there. Adding a 14k or 18k nib to this pen would not improve it's performance, just make it cost more. Yes, this is a personal opinion, but so is everything else about a fountain pen.
The El Grande is a large pen, but it doesn't have to be a heavy weight. It can easilly be brought in at less than 25-grams by shedding most of the metal and closing both ends of the pen. I recently saw a photo of one on the PMG site that was 22-grams. Compare that with a stock Baron that runs in the 45-50 gram range.
