1. Both spas have enough filtration to maintain clean/clear water as long as you are keeping up on the water-care maintenance of course. The Glow uses a single 65 sq ft filter and the prodigy uses (3) 30sq. ft filters but water does not bypass the filters like it does in the Glow and most other spas on the market. The "no-bypass" system in the Jetsetter, Prodigy, Sovereign, and the rest of the Highlife collection has positives and negatives in my opinion....a positive would be the water is filtered constantly throughout the day and is also being filtered during usage, BUT if filters become dirty and/or clogged IT WILL effect jet pressure/performance. a positive would be with more filters you can rotate them to achieve longer life, a negative would be when it comes time to clean and/or replace them you have 3x, 4x or 5x more filters to clean or purchase depending on what Highlife collection model you pick......As you can see here it is really a '6 in one hand' or 'half a dozen in the other' type of scenario meaning again in my opinion only, the type of filtration between both models should have little to no bearing on what model is selected, I'd concentrate more on the feel of the actual jets during a wet test, price, comfort-ability in the spa itself, etc. before I worried about filtration because again both will work just fine as long as you are doing the water-care maintenance.
2. The Highlife Collection was/has always been built with the Quality > Quantity mind-set....Hot Spring's use to have like 5 models in total but because the way the market has shifted along with customer mindset which is basically "Bigger is better" "more is better" mentality they had to bring out the Limelight & Hot Spot collections in order to maintain a strong hold within the market. Wet Test both models to see which you prefer...I've said it 100 times and I'll say it again, a Wet Test is NECESSARY when buying a spa, I've had people who PREFER the jets in a $8,500 Limelight 'Flair' model to the jets in a $14,000 Grandee and of course vice-versa, It's soooo subjective you really need to try them for yourself in my opinion, like TMan was alluding to above, specs on paper mean almost nothing.